During the Second World War the Sloedam was the only connection between the former Island of Walcheren and the South-Beveland peninsula. At that time, the causeway of 1,200 metres long and less than 40 metres wide was of utmost strategic importance. The German troops defended the Sloedam fiercly.

By October 1944 almost all the land surrounding the Scheldt estuary had been cleared of German control. Only the German coastal batteries on the island of Walcheren prevented the Allies from making use of the port facilities of Antwerp. Walcheren was connected to the South-Beveland peninsula by the strategic Sloedam. The causeway of the Sloedam became the scene of heavy fighting.

The liberation of the island of Walcheren started over land on 31 October with an attack on the causeway by the Canadian 2^nd Infantry Division on the German defenders. The Black Watch of Canada, the Calgary Highlanders and Le Régiment de Maisonneuve of the Canadian 5^th Infantry Brigade successively fought to a standstill and suffered many casualties. On 2 November the Canadian troops were relieved on the causeway by the 1^st Battalion Glasgow Highlanders of the Scottish 52^nd Lowland Division who continued the battle. However, they were halted as well.

To support the stalled offensive, it was decided to surprise the German units on the Walcheren side by means of a night attack from the small harbour of Zuid-Kraaijert near Nieuwdorp. During the night of 2 and 3 November Scottish soldiers of the 6^th Battalion the Cameronians, crossed the waters and the mud slabs of the Sloe, two kilometres south of the causeway. This surprise amphibious landing, codenamed Operation Mallard, was successful. The German troops did not expect this outflanking movement and had to withdraw. On the causeway they were now also able to gain ground. On 3 November in the afternoon the causeway finally fell into Allied hands. The battle of the Sloedam was won

This hard fought success by the Canadian and Scottish soldiers enabled the 6^th Highland Light Infantry to pass through and continue the advance to liberate the northern part of Walcheren.