In May 1944 the regiment was converted to three field artillery battalions as part of an Army-wide reorganization.

The 535th was deployed to Europe, arriving in France on 3 January 1945 and returning to New York for demobilization on 27 November 1945.

[1][6][7] The lineage of the 250th Coast Artillery traces back to the 1st California Infantry Regiment, which served in the American Civil War.

The regiment's lineage continued with the formation of the Coast Artillery Corps (CAC), California National Guard (CANG) on 19 April 1909.

Subsequently, this unit was redesignated as the 1st Coast Defense Command (CDC) (1917), 1st Provisional Battalion, CAC, CANG (date unknown), 1st CDC (1921), and 250th Coast Artillery (1923).