Treblinka prisoners on their way to the gas chamber. Treblinka was an extermination camp, built and operated by Nazi Germany in occupied Poland during World War II. It was in a forest north-east of Warsaw, 4 km (2.5 mi) south of the village of Treblinka in what is now the Masovian Voivodeship. The camp operated between 23 July 1942 and 19 October 1943 as part of Operation Reinhard, the deadliest phase of the Final Solution. More Jews were murdered at Treblinka than at any other Nazi extermination camp apart from Auschwitz-Birkenau.