In 1925, Greece and Bulgaria were not friends. They had fought each other during the First World War and those wounds had not yet healed. Tensions were perpetually high along the border, especially along an area called Petrich. Those tensions reached a boiling point on October 22, 1925, when a Greek soldier chased his dog across the Bulgarian border and was shot dead by a Bulgarian sentry. Greece vowed retaliation and, true to its word, it invaded Petrich the very next day. They quickly cleared Bulgarian forces from the area but were halted by the League of Nations, who sanctioned Greece and ordered them to leave Petrich and pay Bulgaria for damages. Greece withdrew its forces ten days later and paid Bulgaria 45,000 pounds.
War duration: (October 23-November 2, 1925) Ten days.
Casualties: Fifty-two dead on both sides.