Analysis of information sources in references of the Wikipedia article "Fort Tyler" in English language version.
Dubbed the Fort Tyler Battery after President John Tyler whose wife, Julia Gardiner Tyler was born on the island, the structure remained in use until it was abandoned in 1920 due to erosion. In 1938, President Franklin Roosevelt declared the tiny island a National Bird Refuge and transferred the battery over to the Agriculture Department, which presumably lasted until World War II when the Navy, having a sizable presence in Montauk at the time, began using the concrete structure for target practice, reducing the historic battery to its current "ruined" condition.
Then, in 1938, the island (the fort is an island at high tide) was declared a National Bird Refuge by President Franklin D. Roosevelt and transferred to the Agriculture Department. However, during World War II, Fort Tyler was used for target practice and was reduced to its present state where it is popularly called 'The Ruins.'
It may have been the shelling of Sag Harbor that led to the construction of Fort Tyler in 1898 at the western tip of Gardiner's Island a point separating Gardiner's Bay from Block Island Sound. The old fort is now referred to by sailors as the 'ruins.' Closed after World War I in 1921, the fort became a target for live practice bombing runs during World War II. Live ordinance is reportedly still there, or so a 'danger' sign warns.
Closed in the late 1920s. Status of batteries in 1921 was; Battery Smith, 2 - 8" Disappearing, 2 - 5" Pedestal.
