What Is 1st Army

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Last updated: April 15, 2026

Quick Answer: The First Army is a field army of the United States Army, established on August 10, 1918, during World War I, and has played a key role in major conflicts including D-Day and Operation Desert Storm.

Key Facts

Established on August 10, 1918, during World War I under General John J. Pershing
Led the U.S. ground assault during the D-Day invasion in Normandy on June 6, 1944
Headquartered at Fort Gillem, Georgia, as of 2023
Commanded over 1 million troops during World War II operations in Europe
Currently serves as a training and readiness command for the U.S. Army Reserve and National Guard

Overview

The First Army is one of the oldest and most decorated field armies in the United States Army. Originally formed during World War I, it has served as a central component in major U.S. military operations across the 20th and 21st centuries. Its legacy includes pivotal roles in both World War II and modern training missions.

Today, First Army functions primarily as a training and mobilization command, ensuring reserve and National Guard units are combat-ready. It operates under U.S. Army Forces Command (FORSCOM) and supports the readiness of over 200,000 soldiers. Its mission has evolved from direct combat leadership to force generation and operational support.

Founded on August 10, 1918, during the final months of World War I, to coordinate American Expeditionary Forces under General John J. Pershing.
Played a central role in the D-Day invasion of Normandy on June 6, 1944, leading the U.S. First Army under General Omar Bradley.
Commanded more than 1 million troops during the European Theater of Operations, including the Battle of the Bulge in late 1944.
Was headquartered at Fort Gillem, Georgia, before relocating elements to Rock Island Arsenal, Illinois, in the 2010s.
Currently oversees training for National Guard and Army Reserve units across 27 states, ensuring deployment readiness.

How It Works

First Army's current structure emphasizes training, readiness assessment, and mobilization support rather than direct combat operations. It partners with reserve component units to validate their preparedness for deployment.

Reserve Component Training: First Army conducts command post exercises and field training to certify National Guard and Reserve units for deployment, ensuring compliance with Army standards.
Operational Command: It provides cadre and evaluators during Warfighter exercises, simulating real-world combat scenarios to test unit effectiveness and logistics planning.
Readiness Oversight: First Army monitors unit training progress through the Army Force Generation (ARFORGEN) cycle, tracking milestones over 36-month deployment windows.
Geographic Reach: The command spans two subordinate divisions: First Army Division East and First Army Division West, covering all U.S. states except those in the Pacific region.
Partnership Model: It collaborates with state adjutants general and FORSCOM to align training objectives with national defense strategy and theater combatant commands.
Historical Evolution: From battlefield command in WWII to a modern support role, First Army transitioned in the 1990s following the end of the Cold War and military restructuring.

Comparison at a Glance

Below is a comparison of First Army’s historical and modern roles, highlighting key shifts in mission, structure, and operational focus.

Aspect	World War II Era	Modern Era (Post-2000)
Primary Mission	Direct combat command during major offensives in Europe, including Normandy and the Battle of the Bulge.	Training, readiness, and mobilization of Reserve and National Guard units.
Command Size	Over 1 million soldiers under operational control during peak WWII operations.	Supports up to 200,000 reserve component soldiers across annual training cycles.
Headquarters	Mobile field HQ in France and Germany during WWII; later based in Europe.	Headquartered at Rock Island Arsenal, Illinois, with regional divisions.
Leadership	Led by General Omar Bradley during D-Day; later by Courtney Hodges during the push into Germany.	Currently commanded by a lieutenant general under FORSCOM oversight.
Geographic Scope	Operated across Western Europe, including France, Belgium, and Germany.	Covers the continental U.S., divided into East and West divisions for regional management.

While First Army no longer leads troops in combat, its role in ensuring national readiness remains critical. The shift from battlefield command to training reflects broader changes in U.S. military doctrine, emphasizing preparedness over permanent standing combat formations.

Why It Matters

First Army’s transformation underscores the evolving nature of U.S. military strategy, where readiness and rapid mobilization are as vital as frontline combat units. Its contributions continue to shape national defense capabilities.

Ensures combat readiness of reserve forces, enabling rapid deployment during national emergencies or overseas conflicts.
Reduces strain on active-duty forces by maintaining a trained, scalable reserve component.
Plays a key role in disaster response within the U.S., supporting civil authorities during hurricanes and other crises.
Validates units for deployment to regions like the Middle East and Eastern Europe under U.S. Central and European Commands.
Preserves the legacy of American military leadership from WWII through modern training doctrine.
Supports interoperability between National Guard, Reserves, and active-duty forces during joint operations.

From commanding vast armies in Europe to building the foundation for modern readiness, First Army remains a cornerstone of U.S. military effectiveness and strategic flexibility.