Greece became a belligerent in World War II when it was it was invaded by Italy on 28 October 1940. A British and Commonwealth expeditionary force was sent to support the Greeks which eventually totalled more than 60,000 men. British forces also garrisoned Crete, enabling the Greek Fifth Cretan Division to reinforce the mainland campaign. This arrangement suited the British: Crete could provide the Royal Navy with excellent harbours in the eastern Mediterranean, and the Ploiești oil fields in Romania would be within range of British bombers based on the island. The Italians were repulsed without the aid of the expeditionary force. A German invasion in April 1941 overran mainland Greece and the expeditionary force was withdrawn. By the end of the month, 57,000 Allied troops were evacuated by the Royal Navy. Some were sent to Crete to bolster its garrison, although most had lost their heavy equipment.