Insignia Description
A Silver color metal and enamel device 1 1/8 inches (2.86 cm) in height overall consisting of a shield blazoned: Sable, in fess an anchor bearing two oars in saltire, between two increscents all Argent. As an augmentation on a chief indented of the last a bend between a lion rampant in chief and a fleur-de-lis in base all Gules.

Symbolism
This regiment has a continuous history from 1846 when Company "A" was organized. At that time the color of the facings of the Corps was black, which has therefore been taken as the color of the field of the shield. Company B was organized in 1861 and both companies served throughout the Civil War in the Army of the Potomac where they were engaged in pontoon bridge building. The Civil War service is represented by the badge of the Engineers and Pontoniers of the Army of the Potomac, an anchor behind two crossed oars in silver. The two crescents are taken from the arms of General Winfield Scott (a silver star between two silver crescents on a bend) and show the service of Company A in Mexico under that General. During World War I, the regiment was cited by the French government for distinguished service at Menil-la-Tour, Cantigny and Soissons. The bend on the chief is taken from the arms of Lorraine where Menil-la-Tour is situated. Cantigny is in Picardy and the lion is from the arms of that province, while the fleur-de-lis is from the arms of Soissons. The indented partition line represents the entrenchments constructed during World War I, while the colors red and white are the present colors of the Corps of Engineers.

History
The distinctive unit insignia was originally approved for the 1st Engineer Regiment on 20 December 1924. It was redesignated for the 1st Engineer Battalion on 29 January 1941.

Source: The US Army Institute of Heraldry