This is the first detailed account of the rearguard action that took place between 25 and 29 May 1940 at Cassel and Hazebrouck on the western perimeter of the Dunkirk Corridor. By 25 May the decision to evacuate the BEF via Dunkirk had already been taken, Lord Gort, commanding the BEF in France, had given instructions to Lieutenant General Sir Ronald Adam to relinquish his command of III Corps and prepare a perimeter of defense around Dunkirk. As part of the western defensive line of the Dunkirk Corridor, 145 Brigade were deployed to Cassel and Hazebrouck with the instructions to hold the two towns until the last man. Under the command of Brigadier Nigel Somerset, the brigade occupied Hazebrouck with the infantry of 1st Buckinghamshire Battalion and Cassel with the 4/Ox and Bucks Light infantry together with the regulars of the 2nd Battalion Gloucestershire Regiment. Attached to Somersets meager force was a number of units that had previously been part of two of Gorts ad hoc formations—Macforce and Woodforce, and it was with these men that the two towns were fortified against the advancing German armored divisions.While Hazebrouck was overwhelmed very quickly, the hilltop town of Cassel held out for much longer with German forces failing to consolidate any penetration of the perimeter. The book looks closely at the deployment of units in both towns and focuses on the individuals involved in the defense and the subsequent breakout, which ended in capture or death for so many. There are two car tours that explore the surrounding area of Cassel and the deployment of platoons within Hazebrouck. These are supplemented by two walking tours, one in Cassel itself and the second further to the west of the town around the area controlled by B and D Companies of the 2nd Gloucesters. The book is illustrated with ten maps and over 100 modern and contemporary photographs.