Previously the Inspector General of the Army, Constantine was appointed commander-in-chief of the "Army of Thessaly" when the First Balkan War broke out in October 1912. He led the Army of Thessaly to victory at Sarantaporos. At this point, his first clash with Venizelos occurred, as Constantine desired to press north, towards Monastir, where the bulk of the Ottoman army lay, and where the Greeks would rendezvous their Serb allies. Venizelos, on the other hand, demanded that the army capture the strategic port city of Thessaloniki, the capital of Macedonia, with extreme haste, so as to prevent its fall to the Bulgarians. The dispute resulted in a heated exchange of telegrams. Venizelos notified Constantine that "... political considerations of the utmost importance dictate that Thessaloniki be taken as soon as possible". After Constantine impudently cabled: "The army will not march on Thessaloniki. My duty calls me towards Monastir, unless you forbid me", Venizelos was forced to pull rank. As Prime Minister and War Minister, he outranked Constantine and his response was famously three-words-long, a crisp military order to be obeyed forthwith: "I forbid you". Constantine was left with no choice but to turn east, and after defeating the Ottoman army at Giannitsa, he accepted the surrender of the city of Thessaloniki and of its Ottoman garrison on 27 October (O.S.), less than 24 hours before the arrival of Bulgarian forces who hoped to capture the city first.