 During World War II in occupied Poland the town's district of Berezwecz was the location of a massacre of up to 2,000–3,000 Polish prisoners by the Soviet NKVD secret police.As late as 2009 the remains of more than 20 victims probably shot by NKVD after the takeover of the area from Poland were again discovered in a basement of a local church.The first mention of Głębokie in historical sources comes from 1414 and this date shall be considered as time of the founding of the first settlement.