The K-blocks were built as part of the Camp of Beverlo in 1835. Initially, only a few blocks were provided to house the cavalry. Over the years, however, the camp grew and reached its largest size in 1913. By then, 3,000 soldiers and 2,629 horses were housed in the various blocks. By 1936, most of the horses had left the blocks as the Belgian cavalry was modernised by motorisation.

The K-blocks were used as a camp for political prisoners after the occupation of Leopoldsburg. As the internment camp was housed in block 34, it was named K-34. From Leopoldsburg, political prisoners were sent to German concentration camps throughout the war years. Thus, from 1942, the German army command decided to bury all those executed in Belgium in 'the secret cemetery'. This is located on the current military compound. Executions were also carried out in the cemetery, often early in the morning.

During bombing raids in May 1944, the internment camp was spared. According to stories, this was because the Allies knew about the presence of political prisoners in the camp. The resistance was indeed very active in Leopoldsburg, but despite this, no conclusive evidence for this has been found to date. One of the most famous political prisoners in the camp was Marc Neels, better known as cartoonist Marc Sleen. He was in the camp at the time of liberation and even drew portraits of fellow prisoners, such as this one of Frans Houthuys.