In June 1942, engineers began work on Battery Construction No. 239 with Herbert Mayson as contractor. This 2-gun 6-inch battery was located at Coronado Heights along with Battery Imperial. The project cost $219,000. The construction was completed in April of 1943 but the guns did not arrive until December.
The guns were 6-inch Model 1905 Nos. 20 and 24 manufactured by the Watervliet Arsenal. The carriages were barbette Model Nos. 56 and 57 made by York Corporation.
Battery Grant was named in honor of Colonel Homer Blackie Grant of the Coast Artillery Corps who died in 1939.
Taken From of 1940 by Robert D. Zink, The Six-Inch Part of the Modernization Program, Coast Defense Study Group Journal, Vol. 8, No. 2, pgs. 21-39, May 1994.