Complex sentence: To qualify as a pathfinder in the Canadian Army the soldier must pass the Patrol Pathfinder course, which is designed as the most difficult course in the Canadian Army, passed only by the most physically and mentally fit soldiers.
Split into simpler sentences: To qualify as a pathfinder in the Canadian Army, the soldier must pass the Patrol Pathfinder course, which is designed to be the most difficult course in the Canadian Army. It is passed only by the most physically and mentally fit soldiers.