In May 2009, 1st and 2nd Battalions, 12th Infantry Regiment, 4BCT, 4th Infantry Division, deployed to Afghanistan in support of Operation Enduring Freedom X. 1st Battalion was based in the Arghandab River Valley, west of Kandahar City, for the latter eight months of the deployment. Task Force 1-12's area of responsibility was referred to as the "Heart of Darkness" due to its significance as the birthplace of the Taliban, and also due to the inherent complexity of their mission. Much of their fighting was conducted in notoriously dense grape fields, which provided excellent concealment for insurgent forces. The 2nd Battalion was based in the Pech River Valley, Kunar Province, home to the Korengal, Waygal, Shuriak, and Wata Pour Valleys. During its time in the Pech Valley, the 2nd Battalion saw heavy fighting throughout their area of responsibility at the foothills of the Hindu Kush mountains. In June 2010, Task Force 1-12 and Lethal Warrior (2-12), 4th BCT, 4 ID redeployed to Fort Carson, Colorado, after 12 months in Afghanistan.