This United States Marine Corps USMC manual, Marine Corps Tactical Publication MCTP 12-10A Mountain Warfare July 2024, is a reference for all unit commanders and their staffs (trained or untrained in mountain warfare) and all leaders from the company level through regiment or brigade for use in operations in mountainous terrain, snow, or cold weather. This publication references formal, individual, and collective mountain warfare training programs available within the Department of Defense. Not all units’ training plans align with a deployment to Marine Corps Mountain Warfare Training Center (MCMWTC) or the opportunity to train in other mountainous environments. Therefore, this publication identifies the skills that Marines need to be successful in mountainous, snow, or cold-weather environments. During combat, these publications provide Marines with the doctrinal references they need to augment the instruction they receive from their unit’s qualified mountain leaders.