After studying art in London, Hennell taught at schools in the West Country. He applied to become a war artist in 1939 and in 1943, he volunteered to replace Eric Ravilious who had disappeared in Iceland. In 1944 when the British forces advanced out of Normandy, Hennell was one of three artists to go with them. He sent back watercolours of a variety of subjects recording the Allied advance towards the strategically important port of Antwerp, which was taken on 4 September.

On 3 October the Royal Air Force Bomber Command tore a 120-yard breach in the sea dyke at Westkapelle on the heavily fortified island of Walcheren. On 1 November Royal Marine Commandos stormed WestKapelle and by 10 November, after fierce fighting, often waist deep in mud, German resistance ended. The Scheldt and the port of Antwerp were re-opened to shipping on 28 November. This typically rapid watercolour was almost certainly made on the spot. It is signed.