Marine Corps Reference Publication 12-10A.3, Mountain Leader’s Guide to Mountain Warfare Operations, is a reference for trained summer mountain leaders to use during operations in complex, compartmentalized, mountainous, high altitude, alpine, and glaciated terrain. This publication covers terrain; weather; rope skills; rope systems; climbing; fixed ropes; rappelling; casualty evacuation; planning considerations across all warfighting functions; chemical, biological, radiological, and nuclear considerations; glacier operations; and processes used to guide units through mountainous/alpine terrain. It focuses on a standard method of instruction and stresses only the skills necessary for Marines to go into combat.