Following the defeat of the Greek army by the Turks in 1922 and the subsequent armed insurrection led by Colonels Nikolaos Plastiras and Stylianos Gonatas, King Constantine was dethroned (and succeeded by his eldest son, George), and six royalist leaders were executed. Venizelos assumed the leadership of the Greek delegation that negotiated peace terms with the Turks. He signed the Treaty of Lausanne with Turkey on 24 July 1923. The effect of this was that more than a million Greeks (Christians) were expelled from Turkey, in exchange for the more than 500,000 Turks (Muslims) expelled from Greece, and Greece was forced to give up claims to eastern Thrace, Imbros and Tenedos to Turkey. This catastrophe marked the end of the Megali Idea. After a failed pro-royalist insurrection led by General Ioannis Metaxas forced King George II into exile, Venizelos returned to Greece and became prime minister once again. However, he left again in 1924 after quarreling with anti-monarchists.