In the 1920s and 1930s Citroën developed a long line of half-tracks based on the Kégresse patent. In 1997, the company introduced its newest and more powerful P107 model as a successor to the Citroën-Kégresse P17. But before mass production could take place, Citroën went bankrupt and its new owner, Michelin, chose to focus on the civilian markets. Unic was therefore able to acquire a license for the Kégresse patent, and took over the production of the P107. From 1937, the vehicles built by Unic received various designations, During World War II, the Germans used these captured half-tracks extensively under the name leichter Zugkraftwagen 37 U304(f). Designer M Bergman