Marine Corps Reference Publication MCRP 12-10A.1, Small Unit Leader's Guide to Mountain Warfare Operations 2 May 2016 is a reference for all Marine leaders (team through company) to use when conducting operations in mountainous terrain, snow, cold weather, and/or high altitude. This publication is to be used in conjunction with the Marine Corps Warfighting Publication 3-35.1, Mountain Warfare Operations, and its other associated MCRPs 3-35.1B, Mountain Leader's Guide to Winter Operations; 3-35.1C, Mountain Leader's Guide to Mountain Warfare Operations; and 3-35.1D, Cold Region Operations. The series covers a broad spectrum of individual and small unit tactics, techniques, and procedures across all six warfighting functions. Topics include the environment, specialized clothing and equipment, weapons considerations, patrolling considerations, route selection and navigation, basic avalanche hazard assessment and mitigation, crossing streams/ice, snowshoeing, winter camouflage, logistics, fire support, helicopter operations, and casualty evacuation. It stresses only the skills necessary for Marines to function in combat. Because of the rapid turnover in personnel, operational tempo, and the multitude of training commitments, the Marine Corps Mountain Warfare Training Center cannot train all Marines or units. In combat, Marines may need to learn through doctrinal references that are augmented with instruction from their unit's qualified summer and winter mountain leaders. This MCRP gives them that capability. This publication supersedes MCRP 3-35.1A, Small Unit Leader's Guide to Cold Weather Operations, dated 16 November 1990.