In 1915, Britain offered Cyprus to Greece, ruled by King Constantine I of Greece, on condition that Greece join the war on the side of the British. The offer was declined. In 1923, under the Treaty of Lausanne, the nascent Turkish republic relinquished any claim to Cyprus, and in 1925 it was declared a British crown colony. During the Second World War, many Greek and Turkish Cypriots enlisted in the Cyprus Regiment.