9th Coastal Artillery patch

The 9th Coast Artillery was constituted on February 27, 1924, and it became the Regular Army component of the Harbor Defenses of Boston (HD Boston) in Massachusetts.  These defenses also included the 241st Coast Artillery, which served as the Massachusetts National Guard component.

The regiment was organized on July 1, 1924, with its headquarters at Fort Banks in HD Boston. Initially, only the regimental headquarters and headquarters battery (HHB) and Batteries A and C were activated. Over time, additional batteries were activated and assigned to various posts around Boston Harbor.