Fort Baldwin is a coastal defense land battery near the mouth of the Kennebec River in Phippsburg, Maine, United States. It was named after Jeduthan Baldwin, an engineer for the Colonial army during the American Revolution. The fort was constructed between 1905 and 1912 and originally consisted of three batteries. During World War I, Fort Baldwin and Fort Popham held a garrison of 200 soldiers including the 13th and 29th Coast Artillery.