At the beginning of the Second World War, during what was known as the "Phoney War", Britain deployed the British Expeditionary Force (BEF) into France to fight alongside the French army. As part of this force, RAF units operating various aircraft were dispatched to contribute, including two Gladiator squadrons.[18] Initial air operations on either side were limited by the winter weather; however, immediately following Germany's commencement of the Manstein Plan and its invasion of the Low Countries on 10 May 1940, the BEF's Gladiators participated in the Dyle Plan, an unsuccessful counterattack on German forces.[18]