This monograph is more than the story of Marine expeditionary operations in Afghanistan. It describes who our nation's enemies are; how America became involved in the Global War on Terrorism; and how the Marine Corps struggled to acquire a major role in Operation Enduring Freedom, as well as the actions of Marines and sailors who helped prosecute the air and ground campaigns against Taliban and al-Qaeda forces. In the latter regard, we see the 15th Marine Expeditionary Unit, already forward deployed on 11 September 2001, ready to conduct a noncombatant evacuation operation, secure a forward operating base, or provide a quick reaction force for joint special operating forces conducting the initial offensive action of the war. The 15th Marine Expeditionary Unit then combined with the 26th Marine Expeditionary Unit and quickly maneuvered from the Mediterranean to form a provisional Marine expeditionary brigade known as Naval Expeditionary Task Force 58. Working simultaneously under the direction of U.S. Central Command's land and maritime component commanders and in association with joint special operations forces, Brigadier General James N. Mattis and his force embarked on a sequence of operations in southern Afghanistan. These included, but were not limited to, establishing Forward Operating Base Rhino, interdicting enemy lines of communications along Highway 1, occupying Kandahar International Airport, securing the American embassy in Kabul, detaining several hundred prisoners of war, and supporting special operations forces during numerous sensitive site exploitation and special reconnaissance missions. The monograph also describes the 13th Marine Expeditionary Unit's rapid reinforcement of Coalition forces during Operation Anaconda, only days after Task Force 58's disbandment. Although events did not afford the Marines an opportunity to engage the enemy in heavy combat, their contribution in southern Afghanistan was nonetheless significant. From a strategic perspective, the arrival of a sizable conventional force demonstrated America's resolve to confront the sponsors of terrorism directly and signaled an end to Taliban rule. From an operational perspective, Task Force 58 successfully blocked the western escape route from Kandahar and threatened the enemy's last remaining urban stronghold. As Lieutenant General Gregory S. Newbold, former director of operations for the Joint Chiefs of Staff, later observed: The insertion of Task Force 58 had a deep psychological impact on the Taliban and al-Qaeda-they were confronted with a military situation which now unhinged any hope they had for a gradual pullback from the north and a chance to hold from their area of greatest strength. . . . The insertion of Task Force 58 fundamentally changed the equation for the enemy from one of grim hope to hopelessness. The strategic agility and operational reach showcased by the Navy amphibious squadrons and Marine expeditionary units validated the utility of task-organized expeditionary forces, particularly in respect to the effectiveness of long-range, ship-to-objective maneuver. These combined achievements contributed directly to the subsequent deployment of expeditionary strike groups in 2003. As a result, today's naval services are now in a better position to address emerging crises around the globe, regardless of whether they occur in littoral or landlocked regions of the world. Colonel Nathan S. Lowrey began his military career as an infantry officer, serving first as a rifle platoon commander in Panama during Operation Just Cause and then as a recruiting officer in Portland, Oregon. After transferring to the Reserves to attend graduate school, he joined the History Division's Field Operations Branch in 1998 and subsequently deployed to document operations in Kosovo, Afghanistan, and Iraq. He joined the Histories Branch as a civilian writer in 2005 and later served as head of the Field and Oral History Branch from 2008 to 2010.