This is a United States Army First Army shoulder sleeve insignia or patch.

It is the oldest and longest established field army in the U.S. Army.

The insignia features the letter 'A' for Army and also as the first letter of the alphabet.

The full-color patch is worn on the left sleeve of the uniform coat.

Patches worn on the right shoulder denote former wartime service, often referred to as "combat patches". The design is officially hallmarked and approved by the U.S. Institute of Heraldry.