Technically not "abandonned" and no longer either a windmill or a lighthouse. It is now a museum.
In 1838, The Battle of the Windmill was crucial and a bloody battle in the complex struggle between the "Family Compact" and the "Reformers" for control of the British colony of Upper Canada.
During a four-day period in November, 1838 British troops and local militia defeated an invasion force of 300 American " Hunters " and Canadian rebels. The Battle of the Windmill victory prevented the invasion force from capturing Fort Wellington, Ontario, and cutting the St. Lawrence communications link, which would have left Upper Canada open to invasion.
At the Windmill, 250 invaders faced over 600 British troops and militiamen for 4 days of battle. By the 5th day, they faced 1000 British troops. By the end of that day, 50 invaders were dead, a few slipped off into the night, and 197 faced trial. Forty were aquitted, 11 were executed, 86 were convicted but later pardoned, and 60 were sent to the penal colonies in Australia.
The windmill was built in the 1820s. In 1873, the windmill became a lighthouse. It was deactivated in 1973 and, in 1996, the museum opened.