Incident at Petrich The incident at Petrich , or the War of the Stray Dog , was a Greek – Bulgarian crisis in 1925 , in which there was a short invasion of Bulgaria by Greece near the border town of Petrich , after the killing of a Greek captain and a sentry from Bulgarian soldiers . The incident ended after a decision of the League of Nations . Background . The relations between Greece and Bulgaria had been strained since the start of the 20th century . There were minority problems between the two countries , also problems about the Macedonian issue and the activity of the Komitadjis . All these problems caused many disputes and many border conflicts between Greece and Bulgaria . The climate was tense and escalation could happen at any time . The incident . There are two versions of how the incident started . According to some sources all started on October 19 , when a Greek soldier ran after his dog , which had strayed across the border from Greece at the pass Demirkapia on Belasitsa ( in Bulgarian ) / Belles ( in Greek ) ; thus , it is sometimes referred to as the " War of the Stray Dog " . The border was guarded by Bulgarian sentries , and one of them shot the Greek soldier . On the other hand according to other sources , the Greco - Bulgarian frontier incident was caused when Bulgarian soldiers violated the Greek borders , attacked a Greek outpost at Belasitsa / Belles and killed a Greek captain and a sentry . Bulgarian and Greek reaction . Bulgaria explained that the firing was due to a misunderstanding and expressed its regret . In addition , the Bulgarian Government proposed the formation of a mixed commission of Greek and Bulgarian officers to investigate the incident , but the Greek Government declined it as long as Bulgarian troops remained in Greek territory . Also , the Greek dictatorial government under General Theodoros Pangalos issued an ultimatum to Bulgaria giving a time limit of 48 hours Greece in its ultimatum demanded : In addition , Greece sent soldiers into Bulgaria to occupy the town of Petrich with the object of enforcing the Greek demands for satisfaction . International intervention . Fighting between Greek and Bulgarian forces started and Bulgaria appealed to the League of Nations to intervene in the dispute . Some chetas of Internal Macedonian Revolutionary Organization ( IMRO ) , together with the sentries , organised defence lines against the Greeks near Petrich . Volunteers and war veterans from the whole region were summoned to join the resistance . On the other side Greece made it clear that it was not interested in Bulgarian territory , but demanded compensation . According to the newspapers of that time the town of Petrich was captured , but according to some other sources , the League of Nations sent a telegraph to both countries ordering them to stop their armies just few hours before Greeks launched their attack to Petrich . The League ordered : Both countries accepted the decision , although Greece complained about the disparity between its treatment and that of Italy in the Corfu incident at 1923 , since the decision showed that there were two different rules in the League , one for the Great Powers , like Italy , and another for the smaller , like Greece . The compensation that Greece had to pay for material and morale damage was £45 , 000 and should pay them in two months . Over 50 people were killed before Greece complied , mostly Bulgarian civilians .