The following are events related to the Global War On Terrorism (GWOT) that took place on this day.

2004

• Start of Operation Wolfhound Trap II in Iraq

2007

• Operation Northern Venture in Iraq

2008

• The Marine Corps involuntarily activated 870 Marines from the Individual Ready Reserve (IRR), most for duty in Iraq. Military occupational specialties called up included motor transport, communications, engineers and some artillery.
• Regimental Combat Team 5 (RCT-5) assumed operational control of a large portion of western Al Anbar Province in Iraq. RCT-5, based out of Camp Pendleton, California, replaced RCT-2. RCT-2 returned to Camp Lejeune, North Carolina, by the end of the month after spending 13 months in Iraq in support of Operation Iraqi Freedom.

Casualties on January 21:

• PALACIOS, GABRIEL TREMINO – January 21, 2004
• PARKER, JAMES DAVID – January 21, 2004
• CHILDRESS, KYLE WILLIAM – January 21, 2005
• LUSK, JOE FENTON II – January 21, 2005
• MATUS, ANDREW GARY – January 21, 2007
• MORRIS, DARREL JAMES – January 21, 2007
• SANCHEZ, EMILIAN DAMIAN – January 21, 2007
• SINGER, CHRISTOPHER GREG – January 21, 2012