Fort McKinley (Maine)
Fort McKinley is a former United States Army coastal defense fort on Great Diamond Island, Maine in Casco Bay, which operated from 1873 to 1947. It was named for President William McKinley. It included a sub-post, Fort Lyon, on Cow Island, just north of Great Diamond Island. Fort Lyon was named for Nathaniel Lyon. Both forts were part of the Coast Defenses of Portland, renamed the Harbor Defenses of Portland in 1925, a command which protected Portland's port and naval anchorage 1895–1950. In 1946, Fort Lyon was closed and turned over to the City of Portland. After Fort McKinley's closure, it was transferred to the United States Navy, which sold the site to private interests in 1961. The Fort McKinley Historic District was listed on the National Register of Historic Places in 1985.
History
Construction and armament
The Board of Fortifications, often called the Endicott Board, recommended a comprehensive program of new fortifications in 1885. Forts McKinley and Lyon were among the results. Construction on Fort McKinley began in 1897 and was complete by 1906. Fort McKinley totaled resulting from two land purchases in 1873 and 1901. The fort was divided by Diamond Cove into a North Fork and a South Fork. The entirety of Cow Island was acquired by the government in 1873; Fort Lyon was built on of it and was complete by 1909.Fort McKinley was completed by 1906 with nine gun batteries as follows:
North Fork:
| Name | No. of guns | Gun type | Carriage type | Years active |
| Ingalls | 8 | mortar M1890 | barbette M1896 | 1904-1942 |
| Berry | 2 | gun M1888 | disappearing M1896 | 1901-1943 |
| Thompson | 3 | gun M1888 | disappearing M1896 | 1902-1942 |
| Acker | 2 | gun M1897 | disappearing M1898 | 1902-1943 |
| Farry | 2 | gun M1898 | masking parapet M1898 | 1902-1920 |
South Fork:
| Name | No. of guns | Gun type | Carriage type | Years active |
| Weymouth | 3 | gun M1888 | disappearing M1896 | 1901-1942 |
| Honeycutt | 2 | gun M1888 | disappearing M1896 | 1901-1942 |
| Carpenter | 2 | gun M1900 | pedestal M1900 | 1906-1917, 1919-1947 |
| Ramsay | 2 | gun M1898 | masking parapet M1898 | 1902-1920 |
Fort Lyon was completed by 1909 with two gun batteries as follows:
| Name | No. of guns | Gun type | Carriage type | Years active |
| Bayard | 3 | gun M1903 | disappearing M1903 | 1907-1917 |
| Abbot | 3 | gun M1903 | pedestal M1903 | 1909-1946 |
At Fort McKinley, facilities supporting an underwater minefield were built on the South Fork and at Fort Lyon; the 3-inch guns at both forts were intended to defend the minefield against minesweepers. Construction of the original barracks and administration buildings at Fort McKinley began in 1902-1903 and lasted through 1906. This construction phase was sized for four companies. Four 109-man barracks were constructed along with four sets of duplex Non-Commissioned Officers' quarters, six sets of duplex officers' quarters, three sets of single family officers' quarters and various administration and support buildings to accommodate a post of this size.
A few buildings were built between 1905 and 1908, and a significant expansion to accommodate seven companies began in 1908-1909 and was largely complete by the end of 1910. The expansion included two additional barracks, one of which was a double barracks, four more sets of duplex NCO quarters and a ten-man Bachelor Officers' Quarters. At this point, the fort had the capacity for 17 officers, 18 married NCOs, and 788 enlisted men. The existing hospital and guardhouse were expanded in 1910 to accommodate the increased population.
World War I
During World War I, the forts were manned by artillery companies of the Coast Artillery Corps and Maine National Guard troops. After the American entry into World War I in 1917, the forts were partially disarmed so the guns could be shipped to the Western Front in France. Four of the eight mortars of Battery Ingalls were removed for conversion to railway artillery. This was done with most mortar batteries; with four mortars in each pit the reloading time was excessive due to crowding of men and equipment. So, mortars were removed to leave two mortars per pit. The mortars were not shipped to France; most railway mortars remained in reserve through World War II. Some of Fort McKinley's 8-inch guns were dismounted for railway conversion, but never left the fort and were later remounted. The two 6-inch guns of Battery Carpenter and Fort Lyon's three six-inch guns were removed to be mounted on field carriages; all were shipped to France and later returned to the United States, with Battery Carpenter's guns returning to Fort McKinley. The Fort Lyon guns were eventually used elsewhere on new mountings in World War II. A history of the Coast Artillery in World War I states that none of the regiments in France equipped with 6-inch guns completed training in time to see action before the Armistice.In 1920 Fort McKinley lost both of its 3-inch gun batteries due to obsolescence; this was part of a general removal of all Driggs-Seabury gun M1898 and their unique masking parapet mountings from service. The masking parapet mount was a simple form of disappearing mount; on 3-inch guns it could not be retracted in action and was locked in the up position after a few years in service.