by the time the united states became involved in world war ii, adolf hitler and the axis forces had control over a large portion of europe, asia and north africa. if the allied forces were to stand a chance, there would have to be several full-scale landings. the u.s. navy decided that to do the job right required sending in their own. they needed men to reconnoiter the landing beaches, take note of obstacles and defenses and ultimately guide the landing forces in. later, during the war, the army engineers passed down demolition jobs to the u.s. navy. they were to clear any obstacles and/or defenses in the near shore area, beginning a tradition that continues today.