Józef Kosacki (1909–1990) – Inventor of a mine detector

The first years of World War Two brought the scourge of many military and civilian casualties on minefields. The fight for human life prompted the invention of an electric mine detector, which was designed by Lieut. Józef Kosacki, an engineer. However, the identity of the creator of the device that saved thousands of human lives was kept secret for years.

Józef Kosacki Józef Kosacki graduated from the Faculty of Electrical Engineering at the Warsaw Technical University in 1933. After graduating, he worked at the National Institute of Telecommunications in Warsaw until the outbreak of war. In early September 1939 he enlisted in the army as a volunteer. Owing to his skills he was assigned to the Technical Group in the Special Liaison Unit. It was tasked with, among other things, relaunching the Polish Radio’s Warszawa II station, which broadcast Warsaw’s President Stefan Starzyński’s speeches throughout the defence of the capital, after the station had been damaged by Germans. War fortunes led Józef Kosacki to join the Polish Armed Forces in Great Britain. It was there, between 1941 and 1942, that he constructed a mine detector. Training ground tests proved the Polish mine detector to be the best, leaving far behind similar equipment designed by six British engineers. The inventor’s identity was kept strictly secret to protect his family remaining in Poland from German repressions. The instrument itself was officially known as the Polish Mine Detector.

Lieut. Kosacki’s electric mine detector consisted of headphones, a metal box with a wave generator, a rucksack, a 202 cm-long bamboo pole hollow on the inside, an elliptic detecting disk with coils and a regulatory box. The device worked on the basis of an electric bridge, whose balance was upset when it came close to a metal object. A handheld portable mine detector designed by engineer Kosacki turned out to be a watershed – it was easy to operate, fast and effective. It was used on a large scale for the first time in North Africa, during the battle of El Alamein in 1942. With 500 mine detectors built by engineer Kosacki, British troops crossed German minefields in a split-second and surrounded the enemy. During the hardest and most merciless tests on the battlefields of World War Two, Kosacki’s mine detector proved unparalleled. It was so efficient that it continued in operation (with minor modifications) for another fifty years in many armies across the world.

Kosacki's mine detector In 1947 Józef Kosacki returned to Poland. First he worked at the Industrial Telecommunications Institute, and then at the Institute for Nuclear Research in Świerk near Warsaw. Along with his professional work, he lectured at the Military University of Technology. After the war he continued to hide the fact that he invented the mine detector, fearing repressions of Polish authorities. The whole truth about the wartime Polish Mine Detector and its later versions produced all over the world could be revealed only after 1989.

Józef Kosacki died on 26 April 1990 in Warsaw.

Interesting facts

Józef Kosacki relinquished patent rights to his invention, making it a gift to Great Britain.


2005 the Military Institute of Engineer Technology was named after Professor Józef Kosacki. The school exhibits the Polish mine detector’s original prototype.


Until recently, the Polish army used mine and metal detectors: W-2P, W-3P, W-4P, which were later versions of engineer Józef Kosacki’s design.


During performance tests of mine detectors filed with the British military authorities in 1941, the device had to, among others, collect 1 penny coins scattered on the lawn. The Polish mine detector proved to be the best by collecting all the coins at the shortest time.

/ National Technology Museum in Warsaw