The Marines have been involved in many conflicts, and had important roles in key battles such as Tripoli, Iwo Jima, Guadalcanal, and Inchon Bay. Every Marine receives infantry training to be ready for battle at all times. Marine Corps training is also known for being especially challenging; at 13 weeks long, Marine Recruit Training is the longest basic training of the six military branches. United States Marines place a large emphasis on morale. This is reflected in their motto, "semper fidelis" (meaning "always faithful"), often shortened to "semper fi".