- British aircraft on the Western Front are ordered to use distinguishing marks. Aerial warfare is still in its infancy, and from the ground it is difficult to distinguish between friend and foe. Britain considers using the St George’s Cross, but decides otherwise, due to its similarity to the German Cross Pattee adopted by the Imperial German Flying Corps in late September. The Union Flag is painted on aircraft wings, fuselage, sides or rudders, but is replaced the following month by a roundel.