All activities are timed and scored: marching tens of kilometers with equipment and weapon in all weathers, obstacle courses, and night navigation exercises. The training is punctuated by firearms training and assault tactics, climbing and rappelling, boat handling, sky diving and scuba diving, explosives instruction, and hand-to-hand combat, which is what Gruner learnt. During the training period, any mistake can instantly disqualify the candidates. The ultimate goal of this training is to detect individuals with the physical, intellectual, and psychological potential needed to serve in the Commandos Marine. Gruner was operational with the French Commandos Marine in Djibouti and Somalia, where he was involved in active combat, especially anti-piracy operations.