Assault Force O – Omaha Beach
After Action Reports
Western Task Force
INVASION OF NORTHERN FRANCE
WESTERN TASK FORCE
From: Commander Assault Force « O »
Enemy Defenses and Opposition Including Beach Obstacles
The terrain in the area where Force « O » landed was of great natural defensive strength, augmented by the addition of many strongly protected and cleverly concealed gun emplacements, machine gun nests, and pill boxes. Slit trenches were dug for defending riflemen, and tank traps and anti-tank ditches intervened between beaches and road exits. In addition, there had been installed in the tidal area, between high and low water, several rows of underwater obstacles consisting of hedgehogs, tetrahedron, Element « C », and pole ramps all inter-connected by barbed wire and thickly sown with mines. The obstacles actually encountered were much more numerous than Intelligence reports had indicated. The artillery and machine guns were generally sited for enfilading fire along the beaches. In some cases they were completely concealed from a direct view from seaward by concrete walls covered with earth which extended well beyond the muzzle of the gun. This acted as a blast screen and prevented them from being located by the dust raised near their muzzles, so that when used with flashless, smokeless powder and without tracer bullets, as they were in defense of OMAHA Beaches, they were exceedingly difficult to detect. These walls, of course, restricted the arc of train of the pieces, but apparently the defenders had accepted this in order to obtain concealment. As a result of this arrangement of gun positions nearly all of the defensive fire was delivered on the beaches themselves or on craft within some two thousand yards of the beach. Several officers noted the fact that craft inshore might be under heavy fire, but those further out were comparatively free from molestation and scarcely a shot fell more than four thousand yards from the beach. The presence of construction materials and more barbed wire indicated that improvement in the defenses was in progress. From prisoners captured it appeared that there were four regiments either actually manning these defenses or taking part in the defense of the beach area. One of them was a coastal defense regiment of the type rated only fair in combat efficiency. The other three, however, belonged to the 362nd Field Division of the German Army, and such troops are generally rated among the best in the world.
To overcome these defenses, plans had been made to destroy or neutralize as many of the guns, machine guns, etc., as possible, by preliminary Naval gunfire and air bombardment, to breach the underwater obstacles under cover of an assault by a single wave of infantry and tanks, and to storm the remaining defenses with succeeding waves of infantry supported by Naval gunfire, the plan included landing light artillery as soon as beach conditions permitted. Circumstances conspired to defeat or nullify the effectiveness of most of these plans. The air bombardment of the beaches was not delivered presumably because of the low cloud ceiling over the beach area just before H hour. Sea conditions caused the lose of a considerable portion of the tanks and many of those that did manage to reach the beach were soon knocked out by enemy artillery and mines. The obstacles were more numerous than had been anticipated and casualties from enemy fire were heavy – so that the demolition parties, despite a gallant effort, failed to breach the obstacles as planned. All of these reduced the assault to the most elementary form of amphibious attack; Infantry landing and attacking supported by Naval gunfire. A Deputy Assault Group Commander in his report of the operation attributed the success of the landing to three factors – the gallantry of the crews of the landing craft who took the Army personnel into the beach, the stark courage of the soldiers who worked their way shoreward through obstacles and enemy fire from artillery, mortars, machine-guns, and rifles, and to the support provided by the Naval gunfire. These are the fundamental factors which will always determine whether the assault succeeds or fails against strong resistance. All the rest are « trimmings », schemes of one sort or another to make it easier for the attacking rifleman, but in the last analysis, it is he and the floating batteries supporting him who win or lose the battle.
When it first became apparent that obstacles in appreciable numbers were appearing on the OMAHA Beaches, special plans for breaching them were devised jointly by the V Corps and the Eleventh Amphibious Force and submitted to CTF-122, and the1st U.S. Army, respectively. It was not until the latter part of April, however, nearly a month later, that approval of these plans was obtained, and troops made available for the special training necessary to their execution. Briefly the plan called for demolition teams consisting of both Army and Naval personnel landing immediately after a wave of tanks and a wave of infantry, and opening gaps through the obstacles using demolition charges and tank-dozers. The time of landing-was calculated so that theoretically the demolition parties would have a minimum of twenty minutes before the rising tide reached the bases of the seaward band of obstacles; all of which were believed to be uncovered at low tide. This was decided because it was believed to be impossible to remove obstacles actually underwater in any quantity within the probable time available in an assault; this without even taking into consideration the interference from enemy fire. The Force Commander would have preferred to land at low tide or even one hour before low tide in order to have allowed the demolition parties more time to deal with the obstacles and to afford some leeway in the event that landing was delayed. Unfortunately, in this respect the requirements on the OMAHA Beaches conflicted with those on the British Force « J » Beach where it was believed necessary to have a minimum of nine or ten feet above the low water mark in order to permit the landing craft to pass over rocks offshore. To allow each Force to have attacked at its most favorable state of the tide would have meant widely staggering the time of H hour, and might possibly have required major changes in the plan because of the minesweeper problem and the limited period of darkness at this time of year. Therefore, a limit was placed upon the difference between the earliest and latest time of landing of the several assault forces and the time chosen for Force « O » was the earliest permitted. Whether or not the demolition parties could have breached the obstacles as planned had the landing been made at or before low water instead of on a rising tide is problematical. As it was the Naval demolition parties suffered forty-one per cent casualties, and it is understood that the Army demolition party casualties were about the same. Had they worked for a longer period exposed to enemy fire, it is possible that they might have been virtually annihilated.
It is believed that an H-Hour earlier in reference to the tidal conditions would have been preferable, particularly for OMAHA Beach. On both of the American beaches the conditions at H-Hour were satisfactory for landing from low water on, as regards the quality of the beach itself; but in the British Sector there were a couple of beaches with rocks and ledges offshore which made a landing prior to about half-tide undesirable.
The military authorities did not consider it desirable that the time for landing should vary more than an hour between the American and British sectors. This dictated an H-Hour for OMAHA and UTAH Beaches which it was estimated would allow about thirty to forty minutes of dry landing on the beach before the water reached the first row of obstacles.
One of the reasons against an H-Hour longer after daylight was that the amount of remaining daylight would not then permit, on D-Day, a second high water period available for unloading. It in not believed that this reason is of great importance and certainly not sufficient to alter the desirability of greater time for working on the beach obstacles.
While the Naval Commander, Western Task Force, cannot pass upon the importance of the Army requirement for not over one hour difference between H-Hour on the various beaches, it appears desirable to point out that for a landing conducted with a large tidal range and with considerable obstacles on the beach, it would be most desirable to have the H-Hour provide as much time as can be made available to work on the obstacles and to clear the beach before the small landing craft, such as LCTs and LCIs, come in to land.
It is still my opinion, first formulated in the Sicily Operation, that broad daylight is the time to land, where our own naval and air superiority is preponderant. In the Normandy Operation our greatest factors of strength were our naval guns and our air force. Each of these offensive components is at its best in broad daylight, when precision in its use can best be obtained. In half-light, neither is fully effective; and for both a longer time-period in which to function in good visibility will increase materially the advantages to be gained.
When we are not in overwhelming strength on the sea and in the air, then landing in darkness is preferred.
The order of landing of the first four waves on all beaches was – DD tanks between H-10 and H-5 minutes; LCT(A)s carrying tanks and tank dozers for obstacle clearance at H hour; a wave of infantry at H+1 minute; and demolition parties at H+3 minutes. DD tanks were to be launched from the LCTs in which they were embarked approximately six thousand yards off shore unless weather conditions prohibited, and were to proceed in to their assigned beaches from that point under their own power. The decision whether to launch at 6000 yards or to close the beaches was left to the senior Army tank officer and senior Naval officer in the LCTs of the two assault groups. Those on the left flank in Assault Group O-1, preceding the 16th RCT, were launched as planned. The sea conditions, however, were such that all but two or three of them foundered before they reached the shore. The responsible officers on the right gauged the sea conditions more accurately and took their LCTs in to a point where the DD tanks grounded as soon as they were launched. Therefore, all the DD tanks preceding the assault troops of the 116th RCT reached the shore. Information is not available as to the exact time of landing or the order of landing waves on all of the beaches. The first landings on EASY RED and DOG GREEN were made at 0635 and it is believed that the leading waves landed on the other beaches at approximately the same time. Due to the state of the sea, the loss of the DD tanks, the absence of five (5) LCT(A)s and damage to others by enemy gunfire, the order of landing was somewhat mixed. Simultaneously with the landing and cessation of the naval gunfire bombardment, the enemy commenced firing. This fire from artillery, mortars, machine guns, and small arms was heavy and accurate, and casualties were numerous. Many of the tanks which had reached the shore line were knocked out, and losses to the infantry advancing shoreward through the obstacles, and to the demolition parties trying to clear lanes through them, were severe. A considerable portion of the equipment of the demolition parties was lost in the landing due to the surf. The limited time for working on the obstacles before they were covered by the rapidly rising tide and the devastating effect of the defensive fire further reduced the effectiveness of the demolition parties. Only five gaps were cleared all the way into the beach, and three part way in, instead of the sixteen planned. Most of these were inadequately marked. The result was that during the high tide immediately following the assault the only opening through the obstacles that was in use for a considerable period was one lane on EASY REDBeach.
At the request of the Commanding General, V Corps, the Commander Assault Group O-2 was directed at H hour to land troops of the 115th RCT at H+4 hours. Thus, all the Landing Force embarked in Force « O » were committed from the beginning of the assault. After the initial waves, landing continued throughout the forenoon and afternoon of D day. Due to the failure of the demolition parties to clear and mark gaps through the underwater obstacles, and to the heavy enemy fire, great difficulty was experienced in getting anyone or anything ashore. Some craft carrying infantry and elements of the Shore Party managed to land their personnel, but the bulk of the craft proceeding shoreward were stopped between the seaward row of obstacles and the line of departure. With the strong tide, fresh wind, and choppy sea, this soon resulted in a mass of craft in which all semblance of wave organization was lost until the Deputy Assault Group Commanders arrived on the scene, took charge of the situation, moved the craft to seaward to give them more room and reformed the waves as best they could. In the meanwhile, most of the tanks which had reached the shore had been knocked out by enemy artillery fire or by mines, or were caught in the obstacles and flooded by the rising tide, and the personnel, both the assault troops and the Shore Party, were pinned down on the beaches just above high water by enemy fire; few, if any, troops actually crossed the beach during the early hours of the forenoon. The supporting destroyers and gunfire support craft stood in as close to the beach as the depth of the water would allow and engaged all the defensive installations which they could locate. Despite this, however, little progress had been made prior to 1100 when there was still considerable machine gun fire, sniping, artillery, and mortar fire on the beaches between the exits, and opposite the exits the condition was critical. A number of enemy strong points in the beach were still holding out and our troops were not able to move inland. The first encouraging news came at 1100 from a message to Commander Transport Division THREE, intercepted by the Force Commander to the effect that German defenders were leaving their posts and surrendering to U.S. troops. Shortly after that another message from a member of the V Corps Staff embarked in a DUKW near the shore line stated that the troops were advancing up the western slope of the exit from Sector EASY. By 1300, COLLEVILLE was taken, and by 1330, a general advance began up slopes of EASY RED and FOX GREEN Beaches. By 1340 the beaches of Sectors EASY and DOG were clear of opposition except for artillery and mortar fire. At 1400, the Commanding Officer of the Engineer Special Brigade Group left the Ancon to set up headquarters on the beach.
Early in the forenoon, reports had been received from the minesweepers stating that the sweep of the Transport Area and the channels for the Bombardment Group from the Transport Area to the 10-fathom curve had been completed with negative results. Because of this, the Force Commander felt that the transports could close the beaches if necessary. However, in view of their prospective early departure from the Assault Area, it was decided that the delay caused by the movement of the ships would result in a net loss rather than a gain, and they were left in the Transport Area until they completed unloading and departed.
Landing of personnel and vehicles from transports and LSTs continued throughout the afternoon of D day. During this time, the beaches were subject to enemy artillery and mortar fire which, while neither heavy nor sustained, was deadly accurate. The fire was obviously observed, because enemy batteries would be silent until craft beached, when there would be a few quick salvos, usually right on the target. This artillery fire caused considerable loss, and was doubly disturbing because neither enemy observers nor batteries could be located. In fact repeated requests for U.S. vessels to cease firing on the beaches were made by personnel ashore and observers to seaward, who thought that it was our own ships firing into our own troops. Actually no U.S. ships were firing at the times the requests were made, and when they did fire, they were firing at targets inland rather than on the beach. About 1430, Commander Force « B » with Convoy B-2, consisting principally of LCI(L)s and HMS Oceanway, stood into the Assault Area. Anchorages close to the beaches were assigned to this convoy and Commander Force « B » was directed to land the troops embarked in accordance with plan, using LCVPs as necessary to unload LCI(L)s. At the same time the Deputy Commanders of Assault Groups O-1, O-2, and O-3 were ordered to provide small landing craft to assist in landing of Force « B ». Meanwhile the LSI(S)s and LSI(H)s which had carried the Ranger Battalions were sailed to the ISLE OF WIGHT, and information was received that the transports of Assault Groups O-1, O-2, and O-3 would complete unloading and be ready to sail by 1700. They sailed about 1800. By 1530, advance elements of the First Division and Twenty-ninth Division Staffs were setting up command posts ashore near the beach exits from Sectors EASY and DOG respectively, and ST. LAURENT was partially occupied in addition to the capture of COLLEVILLE. At 1540, the Oceanway was directed to close FOX GREEN Beach and discharge her twenty (20) LCMs carrying M-4 tanks, these tanks to be attached to the 16th RCT. This was completed by 1715. Convoy Group O-3 and B-1 arrived together about 1600. Although information as to the actual loss of landing craft was meager at this time, indications were that a considerable number were sunk or badly damaged, and at 1700, the Force Commander requested the Commander Service Force to sail ARL-4 to the OMAHA Assault Area as soon as practicable. At 1715, the Commanding General, First Division and his Staff left the Ancon to establish their headquarters on the beach.
By 1730, except for sniping and the recurring artillery and mortar fire, hostile action against the beach area had ceased and the work of organizing the beaches for further unloading was progressing in orderly fashion.
In accordance with the request of the Commanding General, First Division, the 26th RCT was landed in the early evening. All Rifle Companies of the regiment were ashore by 2100. Between 2320 and 2340 the air attack which had been anticipated all day was finally delivered. There were no radar warnings of the approach of the hostile planes and the first information of the impending attack was the sight and sound of an enemy plane which passed over the flagship at low altitude. Only a few more planes came over, however, of which three were shot down. Several bombs were dropped in the Transport Area but caused no damage. This ended D day.
At 0045 D+1, the Commanding General, V Corps, informed the Force Commander that his line was generally along the road from VIERVILLE through ST. LAURENT to about one mile south of COLLEVILLE, and that he intended to attack with the beachhead line as his objective. About 0235, in accordance with a request from the Officer in Command of the Combat Demolition Units, Commander Service Force was requested by dispatch to send additional explosives and demolition equipment for the NCDUs from the United Kingdom by the quickest available means. The response to this request was prompt and efficient. The material was assembled and loaded on a PT which arrived in the Assault Area about 0900 the following day. At 0550, in accordance with the request of the Commanding General, V Corps, Commander Force « B » was directed to land the 175th Infantry on Beach DOG GREEN. This was the last infantry regiment of the First and Twenty-ninth Divisions to be landed, and constituted the Corps Reserve. There was some delay in the execution of this order and the troops did not actually commence to land until between 1000 and 1100. Convoy Group O-4 stood in on the morning watch about twelve hours late. Convoy B-3 and the first of the build-up personnel convoys consisting of the transports Susan B. Anthony, Goethals, Borinquen, and Simonds, likewise arrived. Just to seaward of the Assault Area the Susan B. Anthony struck a mine and eventually sank about 0950. All of the personnel aboard were taken off before she went down. During the forenoon, surveys for the establishment of (the artificial harbor) were commenced. A report from the Commanding General First Army as of 1000 this date stated that the Landing Force was moving forward and now held a line through ST. HONORINE DES PERTES, GOOS LE HAMEL, LOUBIERES and GRUCHY. Unloading of the remaining LSTs and LCT(4)s of Force « O » and Force « B » and of the transports of the build-up convoy continued through the afternoon and evening of D+1. By 2200, all personnel from the Goethals, Borinquen and Simonds had been landed. Except for the transports this unloading was done by LCT(5) and (6)s and Rhino Ferries. In the early evening Convoy Group.
O-5, the last of Force « O », arrived. It also was some twelve hours late. Work progressed slowly because of the obstacles which still impeded access to the beach despite the efforts of the demolition parties who were working on them whenever tidal conditions permitted. In the light of later experience it is regretted that a practice of drying out the LSTs and larger LCTs was not commenced immediately. This would have materially speeded up the unloading and would have freed the LCT(5)s and (6)s and Rhino Ferries for unloading MT ships which were beginning to arrive. ANCXF’s directive stated specifically, however, that LSTs were not to be dried out except in an emergency, and at this stage of the operation it did not appear to the Force Commander that the situation could be so construed.
Between midnight and morning of D+2 day, there ware two air raid alarms; the first about 0105, and the other about 0610. Neither developed into a serious attack although it was believed at the time that some mines had been dropped in the Assault Area. Repeated sweeps, however, failed to detect them. Clearing of obstacles and unloading had continued during the night of D+1, and by 1000 D+2, all LSTs of Force « O » had finished discharging. About 1100 the 5th Ranger Battalion which had landed on DOG GREEN Beach with the 116th Infantry and had been fighting its way steadily westward along the shore line established contact with the survivors of the three Ranger companies which had landed on the POINTE DU HOC to knock out the enemy batteries there. The latter had accomplished their mission, but had been hemmed in within a small area near the tip of the point where they had been under constant enemy attack for more than forty-eight hours. Repeated requests had been received from them for boats to evacuate wounded, additional ammunition, and reinforcements. These requests had been passed to the Commanding General, V Corps, and boats to carry the reinforcements were offered. Gunfire support ships were doing their best to help by delivering supporting fires as requested by the Liaison Officer with the Rangers, but their situation was desperate. (Further account of Rangers may be found in naval gunfire chapter). Finally, on the afternoon of D+1, two boats from the Flagship with medical supplies landed on the POINTE DU HOC and delivered them to the group besieged there.
In this Operation PCs were used as Primary Control Vessels and SCs as Secondary, neither were adequately trained. The PCs had received a few days instructions and in addition to taking part in one large scale exercise, had been taken out several times for special drill as Landing Craft Control Vessels. The SCs had had no instruction and no training. They reported to the Assault Force Commander at PORTLAND after the assembly of the Force was practically completed and while loading was in progress.
In the assault the Control Vessels were faced with a difficult situation. Due to the underwater obstacles landing craft could not beach and retract promptly. Many of them were held up outside of the seaward row of obstacles. Within an hour after the first wave landed it became apparent to those on the scene that the landing schedule could not be maintained and that the entire attack landing plan would have to be discarded insofar as the time element was concerned. Thereafter it became not a schedule, but merely a priority or order of landing. The possibility of this contingency arising had been foreseen in all joint training exercises and in planning for the operation, and the Assault Group Commanders had been directed to instruct and indoctrinate their Control Vessels as to the action to be taken. Nevertheless, the landing craft were allowed to fall into confusion, as wave after wave was dispatched from the line of departure close in on the preceding wave, where the combined effect of the wind and tide soon converted the waves in to a milling mass in which little semblance of order remained. Had it not been for the appearance on the scene of the Deputy Assault Group Commanders and their prompt action in withdrawing and reforming these craft, the success of the entire landing would have been jeopardized.
The reason for the lack of training of the Control vessels is simple – they did not arrive in the theater soon enough. Shortly after the Force Commander arrived in this theater, it became apparent that patrol craft which could act as escorts for landing craft in coastal voyages and also as Control Vessels in amphibious operations were needed. Landing craft were not well adapted to movement in the ordinary British coastal convoys and the British MLs assigned to the Force were too few in number to carry out all the escort duties required of them, and not as well equipped navigationally as our own PCs and SCs. Immediate steps were taken to try to procure an adequate number of U.S. Control Vessels, but for some time the efforts of the Force Commander met with little success and. it was not until almost literally the last minute that a sufficient number of craft arrived and reported for duty. In the interim, makeshift arrangements were made in training exercises by using the British MLs as Control Vessels, but apart from their lack of equipment the British officers were diffident about giving orders to U.S. Naval personnel, and it was usually necessary to place a U.S. Naval officer on board each ML if it were going to exercise a firm control over the boat waves. After a few PCs did arrive in the theater they, like the MLs, were too busily engaged in escorting landing craft between ports to be available for a thorough course of training in the duties of Control Vessels. It had been hoped to give the PCs and SCs assigned this Force some training as Control Vessels after the assembly of the Force and while the Transports and Landing Craft were loading, but as had been previously stated, they were employed up to the last minute for escort duty by Commander Service Force (previously Commander Landing Craft and Bases), under whose control they were operating during the assembly and mounting. When they did arrive at the assembly ports it was too late to do more than provide for their logistic needs and give them their written orders amplified by oral instruction from the Assault Group Commander. Under the circumstances, it is scarcely to be wondered that they were unprepared for the duties they were called upon to undertake. One SC which reported on D-1 Day had no man on board who could send or receive semaphore or flashing light.
That in organizing for any amphibious operation the vessels which are to be employed as Control Vessels be made available to the Force Commander in ample time to enable him to assure himself that they are thoroughly trained. When large numbers of LCTs are to be employed, Control Vessels must include temporary flagships for LCT Flotilla and Group Commanders. The success or failure of the landing may hinge upon how well these craft perform their duty.
That in connection with the employment of Control Vessels, it is believed that the commanding officers of these craft are usually too young and inexperienced to be entrusted with the grave responsibility which may become theirs — as it did in the Assault of Force « O » in this operation. It is considered that in future operations it would be advisable to have a Naval officer and an Army officer f sufficient rank and experience with authority to make decisions involving changes in the assault plan if necessary on an independent craft free to move about in the area between the line of departure and the beach. These officers would be available to take personal charge of the situation there in an emergency, or to authorize departures from details of the landing attack plan in order to take advantage of more favorable conditions on certain beaches. Such officers might well be members of the Staff of the Naval Commander and the Landing Force Commander or their deputies. In this Operation the Deputy Assault Group Commanders did what is proposed above, but they did not have any Army officers embarked with them.
THE GILBERTS OPERATION DEMONSTRATED THE NEED FOR CONTROLLING THE MOVEMENT OF TROOPS, EQUIPMENT AND SUPPLIES FROM SHIP TO SHORE ESPECIALLY WHEN THE LEADING ASSAULT WAVES ARE HALTED AT THE SHORE LINE – SEE COMMENT PAGE 6-5 OF « AMPHIBIOUS OPERATIONS – COMINCH P-001″. AS A RESULT OF EXPERIENCE GAINED AT TARAWA A CHIEF CONTROL OFFICER WAS EMBARKED IN AN SC AT KWAJALEIN TO MAINTAIN MORE ACCURATE CONTROL OF BOAT WAVES, OF TROOPS WHO HAD LANDED, AND THE FLOW OF SUPPLIES. EMBARKED IN THE SC WITH THE CHIEF CONTROL OFFICER WERE (a) A REPRESENTATIVE OF THE COMMANDER OF THE LANDING FORCE EMPOWERED TO MAKE DECISIONS (b) A REPRESENTATIVE OF THE G-4 DIVISION OF THE COMMANDER OF THE LANDING FORCE WITH AUTHORITY TO DETERMINE MATTERS CONCERNING THE FLOW OF SUPPLIES TO THE BEACH (c) A MEDICAL OFFICER OF THE LANDING FORCE CONCERNED WITH EVACUATION OF WOUNDED AND (d) THE COMMANDING OFFICER OF THE LVT BATTALION. LANDINGS AGAINST RESISTANCE HAVE DEMONSTRATED THAT THE RESPONSIBILITY FOR THE CONTROL OF THE MOVEMENT OF TROOPS EQUIPMENT AND SUPPLIES DURING THE ASSAULT SHOULD NOT BE ENTRUSTED TO THE JUNIOR OFFICERS IN COMMAND OF PATROL CRAFT. THIS CONTROL SHOULD BE EXERCISED BY REPRESENTATIVES OF THE ATTACK FORCE AND LANDING FORCE COMMANDERS WITH AUTHORITY TO MAKE THE DECISIONS REQUIRED TO REGULATE THE FLOW OF TROOPS AND SUPPLIES IN CONFORMITY WITH THE TACTICAL SITUATION ENCOUNTERED AT THE BEACH.
That experiments aimed at breaching beach obstacles by bombs or rockets be continued. That it be accepted as a principle that with the methods now developed Naval Combat Demolition Units working under fire in an assault cannot effectively remove underwater obstacles on a front sufficiently wide to permit extensive landings, unless strongly supported by gunfire and aircraft bombing and strafing, or covered by darkness or smoke. Therefore, whenever tidal conditions permit, beach obstacles should be attacked while they are uncovered and preferably after the beaches have been cleared of defensive fire.
That if circumstances make it necessary to attempt to breach obstacles or where the obstacles are few in number. Not only are the
obstacles one of the most difficult factors of the defense to overcome in the assault, but also they impede and delay the landing of vehicles, supplies, and equipment during the follow-up and build-up phase.
IT HAS BEEN THE PRACTICE IN THE PACIFIC TO SUPPORT THE UNDERWATER DEMOLITION PARTIES WITH THE HEAVIEST POSSIBLE BOMBARDMENT. AT KWAJALEIN A DAYLIGHT BEACH RECONNAISSANCE WAS MADE ON DOG DAY AT BOTH HIGH AND LOW TIDES COVERED BY SHORT RANGE BATTLESHIP GUNFIRE. AT SAIPAN BEACH RECONNAISSANCE TOOK PLACE ON D-I DAY AND CONTINUED OVER A LONGER PERIOD SUPPORTED BY HEAVIER NAVAL GUNFIRE. AT GUAM THE RECONNAISSANCE AND UNDERWATER DEMOLITION WORK WAS CONDUCTED OVER A PERIOD OF SEVEN DAYS SUPPORTED BY THE CONCENTRATED FIRE OF LCI(G)S, DESTROYERS, CRUISERS AND BATTLESHIPS. THOUGH THE GEOGRAPHICAL, HYDROGRAPHICAL AND STRATEGICAL CONDITIONS AT NORMANDY DIFFERED COMPLETELY FROM THOSE ENCOUNTERED THUS FAR IN THE PACIFIC, IT IS CONSIDERED THAT WHENEVER POSSIBLE THE WORK OF UNDERWATER DEMOLITION TEAMS SHOULD BE COVERED BY THE HEAVIEST AIR AND GUNFIRE BOMBARDMENT THAT, UNDER THE EXISTING TACTICAL AND STRATEGICAL CONDITIONS, CAN BE BROUGHT TO BEAR.
Sweeping of the Approach Channels to the Assault Area was conducted under the direction of ANCXF although the Force Commander was consulted as to the exact location of the channel and the timing of the sweeping operation. Sweeping of the Transport Area, the Fire Support Areas, and Boat Lanes was conducted under the orders of the Force Commander. The sweeping problem was a difficult one, complicated as it was by the short hours of darkness, the strong tidal currents at right angles to the line of sweep during most of the operation and the limited number of sweepers available. Four minesweeping flotillas were assigned to Force « 0 », each of which was capable of sweeping with six vessels simultaneously. They included two flotillas of Fleet Sweepers swept the Approach Channels and the Transport Area with the YMS Flotilla and BYMS Flotilla following closely astern of them. Upon completion of the sweep of the Transport Area, one of the Fleet Flotillas immediately commenced enlarging the Approach Channel while the other aided by the BYMS commenced the sweep of the Fire Support Area and the Boat Lanes.
The effectiveness of the sweep cannot be judged because no mines were encountered, either in the Approach Channel, the Transport Area, or the Boat Lanes, but the performance of the sweepers in marking the swept channels and Transport Area with Dan buoys was outstanding.
As matters turned out, neither the mines nor the batteries proved dangerous, and the Transport Area could have been moved in to half its actual distance from the shore with impunity. In view of the fact that mines in considerable number were encountered in the Assault Areas both to the eastward and westward of Force « O », the Force Commander is at a loss to determine the reason for the freedom of the area from mining and mine damage, but is duly appreciative of his good fortune.
The various types of mines developed by the enemy show a high degree of skill and ingenuity, and it is worthy of note that most of the losses in the Operation arose from this source. Many of these were due to mines, in all probability, laid by aircraft, and it should be borne in mind that though fighter protection and AA gunfire may preclude the possibility of a successful bombing or torpedo plane attack, as long as there are enemy air fields within range of the Assault Area, it is next to impossible to prevent minelaying in swept channel and anchorages by aircraft at night.
MORE EXTENSIVE USE OF THE AIRCRAFT MINE MAY BE EXPECTED WHEN THE ENEMY AIR HAS BEEN FORCED INTO A STRICTLY DEFENSIVE BOLE.
That efforts be made to develop a minesweeper and sweeping gear which can sweep ahead of a force proceeding at a minimum speed of 12 knots. The present situation of having to have minesweepers precede convoys to the Assault Area by several hours, or else have the convoys follow the sweepers at a speed of 6 to 8 knots, is definitely unsatisfactory.
DD Tanks. The Force Commander can see no justification for the further employment of the DD tanks in an amphibious assault. The element of surprise – the one thing that made them of possible value in this operation – exists no longer. They are far less seaworthy, less navigable and more vulnerable to enemy fire than the landing craft in which they are embarked, hence it is better to land them on the beach as ordinary tanks rather than to have them swim in under their own power. This device may be useful for river crossings, but it is of no value in a landing on ocean beaches.
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