Though Constantine did remain decidedly neutral, Prime Minister of Greece Eleftherios Venizelos had from an early point decided that Greece's interests would be best served by joining the Entente and started diplomatic efforts with the Allies to prepare the ground for concessions following an eventual victory. The disagreement and the subsequent dismissal of Venizelos by the King resulted in a deep personal rift between the two, which spilled over into their followers and the wider Greek society. Greece became divided into two radically opposed political camps, as Venizelos set up a separate state in Northern Greece, and eventually, with Allied support, forced the King to abdicate. In May 1917, after the exile of Constantine, Venizélos returned to Athens and allied with the Entente. Greek military forces (though divided between supporters of the monarchy and supporters of "Venizelism") began to take part in military operations against the Bulgarian Army on the border.