Deadliest Suicide Attack on U.S. Forces in Iraq: Remembering the December 21, 2004 Mosul Bombing

On December 21, 2004, as American troops gathered for lunch inside a large mess tent at Forward Operating Base Marez in Mosul, a suicide bomber slipped inside wearing what appeared to be an Iraqi security forces uniform. Moments later, he detonated an explosive vest in the middle of the crowded dining hall, killing 22 people and wounding more than 70. It remains the single deadliest suicide attack on American forces during the Iraq War.

The bombing struck at the heart of the main U.S. military airfield in northern Iraq, a sprawling installation shared by American troops, civilian contractors, and Iraqi soldiers. The attack unfolded just four days before Christmas, at a time when many service members were looking forward to brief holiday calls home. Instead, the explosion tore through the tent's canvas walls, sending shrapnel, debris, and smoke across the base and triggering one of the most devastating days of the conflict.

A Carefully Planned Infiltration

Investigations later revealed that the bomber had infiltrated the base by exploiting a gap in the perimeter rather than entering through an official gate. The insurgent group Ansar al‑Sunnah, a radical Sunni organization active in northern Iraq, claimed responsibility. The group said the attacker had spent months gathering intelligence on the base and its routines, allowing him to strike at the moment when the dining hall was most crowded.

Early reports suggested the explosion might have been caused by a rocket or mortar strike, but U.S. officials soon confirmed it was a suicide bombing - a tactic that had become increasingly common across Iraq but had never before inflicted such a concentrated toll on American personnel.

The Human Cost

Fourteen U.S. soldiers were killed instantly, along with four American civilian contractors working for Halliburton subsidiary Kellogg Brown & Root. Four Iraqi soldiers also died in the blast. The wounded included 51 U.S. troops, as well as dozens of civilians and Iraqi personnel.

Witnesses described chaos inside the tent. Soldiers overturned tables to use as makeshift stretchers, carrying the wounded into the cold December air as medics rushed to stabilize the injured. Smoke and dust filled the space where moments earlier troops had been eating lunch and sharing conversations about home.

For many units stationed at Marez, the attack was deeply personal. Members of the Maine National Guard's 133rd Engineer Battalion suffered multiple casualties, as did soldiers from the 1st Battalion, 5th Infantry Regiment out of Fort Lewis, Washington. The loss reverberated across the country as families learned that loved ones serving in what was considered a relatively stable region of Iraq had been caught in one of the war's most shocking attacks.

A Turning Point in the Insurgency

The Mosul bombing underscored the evolving sophistication of insurgent tactics. By disguising the attacker in an Iraqi security uniform, Ansar al‑Sunnah exploited the growing reliance on local forces and contractors - a strategy central to U.S. efforts to stabilize Iraq ahead of the January 2005 elections.

Maj. Gen. David Rodriguez, who oversaw U.S. forces in northern Iraq, later emphasized that the attack demonstrated the insurgency's ability to adapt and strike even heavily fortified locations. It also raised urgent questions about base security, screening procedures, and the vulnerability of shared facilities.

A Lasting Legacy

Two decades later, the December 21 bombing remains one of the most painful chapters of the Iraq War. It marked a moment when the conflict's dangers reached deep inside what many troops considered a safe zone, and it highlighted the unpredictable nature of an insurgency willing to sacrifice its own fighters to inflict maximum casualties.

For the families of the fallen, the attack is remembered not only for its scale but for the individual lives cut short - soldiers, contractors, and Iraqi allies who shared a mission and paid the ultimate price.

The Mosul bombing stands as a stark reminder of the human cost of war and the sacrifices made by those who served far from home during one of the most turbulent periods in recent American military history.