The Northumberland Brigade of the Northumbrian Division became the first territorial formation larger than a battalion to fight under its own command when it participated in an abortive counter-attack on 26 April 1915 during the Second Battle of Ypres. It suffered 1,954 casualties and earned a personal congratulation from French. The division had deployed only three days earlier; the rest of its units were attached piecemeal to other formations and immediately thrown into the desperate fighting, earning further praise from French for their tenacity and determination. Several other territorial battalions attached to regular army formations fought with distinction in the defence of Ypres, at the cost of heavy casualties. The three battalions of the Monmouthshire Regiment were temporarily amalgamated into a single composite battalion, as were three battalions of the London Regiment. Battlefield amalgamations were a military necessity which threatened the legal protections on territorial unit integrity.