the La Bassée Canal between Aire and Carvin, a front of , on the flank of Macforce. With insufficient forces to cover the entire area, they had to defend and prepare to destroy 44 bridges. The stream of refugees moving through the area impeded this duty. The water obstacles posed the only natural barrier between the advancing German armour forces and the rear of the BEF, and potential catastrophic defeat. With assets being moved between Polforce and Macforce, the division was unable to fight as a cohesive entity. The divisional history, written by division staff, stated the brigades fought "confused, independent and one‐sided" battles. Most notably, they record the 137th Brigade suffering "grievous casualties" when German forces broke through their positions on the La Bassée Canal. Meanwhile, with the BEF surrounded and the military situation in Flanders having deteriorated, the decision was made to evacuate the BEF from Dunkirk, the only remaining port in British hands. The remnants of the division's brigades retreated north towards the port. On 29 May, the division was assigned to defensive positions along the Canal de Bergues and Nieuwpoort-Dunkirk Canal, on the Dunkirk perimeter. On 1 June, the division faced a major German attack, which involved bitter fighting, artillery barrages and heavy casualties. During the day, the division withdrew into Dunkirk and was subsequently evacuated via the mole or from the beaches. The 2/4KOYLI, the 2/6DWR, and the 2/7DWR had become separated from the division during the move from Rennes and were located on the southern side of the German advance into France. As they were unable to retreat towards or evacuate from Dunkirk, these battalions retreated west across France, with the 2/4KOYLI being heavily engaged in the defence of bridges crossing the Seine at Pont-de-l'Arche. These battalions eventually reached Cherbourg and Saint-Nazaire, and were evacuated as part of Operation Aerial. Home defence After returning to the United Kingdom, the division moved to Manchester, and the process of rebuilding it began. Curtis was reassigned to the 49th Division, and replaced by Major-General Desmond Anderson (previously the GOC of the 45th Infantry Division) on 5 July. In late July, the division relocated to Scotland and was placed under the authority of Scottish Command. The Royal Artillery field regiments from the 49th Division were then assigned to the division, replacing those that were detached prior to the 46th Division's departure to France. This was followed by the