The Greek army was also successful. It retreated according to plan for two days while Thessaloniki was cleared of the remaining Bulgarian regiment. Then, the Greek army counter-attacked and defeated the Bulgarians at Kilkis (Kukush), after which the mostly Bulgarian town was plundered and burnt and part of its mostly Bulgarian population massacred by the Greek army. Following the capture of Kilkis, the Greek army's pace was not quick enough to prevent the retaliatory destruction of Nigrita, Serres, and Doxato and massacres of non-combatant Greek inhabitants at Sidirokastro and Doxato by the Bulgarian army. The Greek army then divided its forces and advanced in two directions. Part proceeded east and occupied Western Thrace. The rest of the Greek army advanced up to the Struma River valley, defeating the Bulgarian army in the battles of Doiran and Mt. Beles, and continued its advance to the north towards Sofia. In the Kresna straits, the Greeks were ambushed by the Bulgarian 2nd and 1st Armies, newly arrived from the Serbian front, that had already taken defensive positions there following the Bulgarian victory at Kalimanci.