The main use of DD tanks occurred on D-Day. They were also used in Operation Dragoon, the Allied invasion of southern France, on 15 August, 1944, Operation Plunder, the British crossing of the Rhine on 23 March 1945 and in several operations on the Italian Front in 1945. DD Tanks were sent to India and the 25th Dragoons were trained in their use, but planned operations against the Japanese in Malaya never occurred.
D-Day
The DD Sherman was used to equip ten tank battalions of British, Canadian and American forces for the D-Day landings. They were carried in Tank landing craft (LCT)s. These could normally carry nine Sherman tanks, but could fit fewer of the bulkier DD's. British and Canadian LCTs carried five tanks, the Americans carried four DD's as their LCT's were shorter at about 120 feet (37 m).
The DD's would be launched around two miles offshore, they would swim to the beaches and overpower German defenses unprepared for attack tanks. In the event, the tank's record was a mixture of success and failure, although they are mainly remembered for their disastrous failure on Omaha Beach.
Sword Beach
On the British Sword Beach, at the eastern end of the invasion area, the DD tanks worked well, as the sea was reasonably calm. The DD tanks were launched 2.5 miles (4,023 m) from shore. Five could not be launched as an LCT's leading tank tore its screen - they were later landed directly on shore - and one tank sank after being struck by an LCT.
Gold Beach
On Gold Beach, the sea was rougher. The tanks of the Sherwood Rangers Yeomanry were launched late, 700 yards (640 m) from the shore. Eight tanks were lost on the way in and by the time the remainder landed, Sherman Crab mine flail tanks had already destroyed the German artillery and machine-gun positions that would have been their objective. The sea conditions meant the tanks of the 4th/7th Royal Dragoon Guards were landed in the shallows. They then drove onto the beach with their screens up so they wouldn't get swamped in the breakers. German anti-tank guns caused heavy losses in some sectors of the beach but the assault was successful.
Juno Beach
On the Canadian Juno Beach, The Fort Garry Horse and the 1st Hussars were equipped with DD tanks, but only those of the 1st Hussars could be launched. They were assigned to the 7th Canadian Brigade, on the western end of the beach. Some of the tanks were launched at 4,000 yards (3,658 m) and some at 800 yards (700 m); twenty-one out of twenty-nine tanks reached the beach. The 8th Canadian Brigade, on the eastern end of the beach, was forced to land without DD tanks because of rougher seas. They suffered heavy initial casualties, but were still able to make good progress.
Utah Beach
DD tanks on Utah beach
On Utah Beach, the DD's were operated by the 70th Tank Battalion. Four of the DD tanks were lost when their LCT was lost to German artillery fire. The remaining tanks were launched 15 minutes late at a point 1,000 yards (914 m) from the beach. Twenty-seven out of twenty eight reached the beach but confusion caused by the massive smoke screen meant they landed around 2,000 yards (1,829 m) from their aiming point and saw little German opposition.
Omaha Beach
At Omaha Beach almost all of the tanks launched offshore were lost, contributing to the high casualty rate and slow progress at that beach.
There were 112 tanks assigned to the first wave at Omaha Beach, with 56 tanks in each of the 741st and 743rd Tank Battalions. Each of these battalions had 32 DD Shermans and 24 other Shermans (including many Sherman bulldozers for clearing obstacles). Starting at about 0540, the 741st Tank Battalion put 29 DD Shermans into the sea, but 27 of these sank and only two made the long swim to the beach. Some of the crews of the sinking tanks managed to radio back and warn following units not to launch as far out. The remaining tanks of the 741st Tank Battalion and all tanks of the 743rd Tank Battalion (except for 4 tanks aboard one LCT that was hit by artillery fire just off the beach) were landed directly on the beach, starting at about 0640.
The DD Tanks were designed to withstand waves up to 1 foot (0.3 m) high; however, on that day the waves were up to 6 feet (2 m) high. These were much worse conditions than the tanks had been tested in and thus they were swamped with water. Also, the tanks of 741st Tank Battalion were released into the sea too far out, about 3 miles (4,828 m) offshore. Considering the inherent difficulty in steering a 35 ton modified tank, it is a tribute to the crews that they got as far as they did. The crews were equipped with emergency breathing apparatus capable of lasting 5 minutes, and the tanks were also equipped with inflatable rafts. Some sources claim that these life-saving measures were ineffective, contradicted by the testimony of survivors. Most of the crews were rescued, mainly by the landing craft of the 16th RCT (Regimental Combat Team) although five crewmen are known to have died during the sinkings.
Until very recently it was believed that most of the DD Shermans of 741st Tank Battalion were sunk immediately, swamped by the seas that were much higher than the operators had practiced with. Some stayed afloat for a matter of minutes; according to the crews one tank swam for 15 minutes before sinking, another "We weren’t in the ocean 10 minutes when we had a problem" Tanks at the other four beaches suffered no such problems. New research suggests that the Omaha tanks were aiming for a church steeple on the visible horizon behind the cliffs. In order to maintain their line of sight it is believed that the tanks had to turn progressively away from the shore to combat the wavefronts pushing them down the beach, putting their sides virtually parallel with the waves/beach. This meant that the protective canvas flotation devices were easily swamped by the waves. If they had kept going directly forward with the front of the tank headed straight for the beach, they may have reached it.
Others believe that the error was on the part of the commanders aboard the ships from which the tanks were launched. They simply gave the order to launch too early, possibly to avoid getting too close to the battle themselves.
Operation Dragoon
The Operation Dragoon landings took place on 15 August 1944. The invasion took place between Toulon and Cannes.
A total of 36 DD-tanks were used by three American tank battalions - the 191st, the 753rd and the 756th. The 756th battalion had eight tanks that were launched 2,500 yards (2,286 m) from the beaches; one was swamped by the bow-wave of a landing craft and one sank after striking an underwater obstacle. The twelve tanks of the 191st battalion were all landed on or close to the beach. The 753rd battalion had 16 tanks, of which eight were launched at sea and successfully reached the shore and eight were landed directly on the beach later in the day,
North West Europe
Sherman DD tanks crossing the Rhine, 24 March 1945
The Staffordshire Yeomanry were converted to DD tanks after D-Day and trained with them in Belgium. On the 26th of October 1944, they undertook a 7-mile (11 km) swim across the Western Scheldt to attack South Beveland, during the Battle of the Scheldt. The DD Tanks' longest operational water crossing took place without casualties, but the tanks had great difficulty in landing - 14 became bogged down in mud and only four were available for action.
Operation Plunder, the crossed the Rhine, began on the night of the 23rd of March, 1945. As well as the Staffordshire Yeomanry, DD tanks equipped the American 736th and 738th Tank Battalions and the British 44th Royal Tank Regiment. Some tanks were lost in the river, but the crossings were considered a success. The tanks were launched from points upstream from their objectives, to take account of the Rhine's strong current, and mats at the objective points (carried across beforehand by LVTs) allowed the DDs to climb the steep, muddy banks of the river.
The DD's last combat, swimming operation was the Staffordshire Yeomanry's crossing of the River Elbe at Artlenburg on the 29th of April 1945.
Italian Campaign
By February 1945, the 7th Queen's Own Hussars in Italy had been trained an equipped with DD tanks, both DD Shermans and DD Valentines. DD Shermans were successfully used in the crossing of the Po River on the 24th of April. On the 28th of April, those tanks still able to swim were used in an assault across the River Adige. During this operation, Valentine DDs were used to transport fuel (their only know use on active service). The tanks continued to be used in combat in the advance towards Venice. There were no further swimming operations, but it was found that the folded flotation screen offered a large seating area, that made the tanks useful troop transports.
The alternative: deep wading gear
Deep wading gear on a Sherman in Normandy, 1944.
Although Duplex Drive allowed the landing craft to release the tank farther from shore, the alternative deep wading gear allowed a tank to drive partially or wholly underwater on the sea floor rather than swim. Deep wading Churchills took part in the 1942 Dieppe raid and deep wading tanks operated on D-Day also. Allied tanks were given waterproofed hulls and air intake and exhaust trunking to allow them to come ashore from shallow water. Tall ducts extended from the engine deck to above the turret top and these needed to stay above water. The front duct was the air intake for the engine and the rear duct vented the exhaust. This device saw use in many amphibious invasions, and was used on light tanks and tank destroyers as well. The US had similar devices for trucks and jeeps.