Mackinac Island ( MAK-in-aw) is an island and resort area, covering 3.8 square miles (9.8 km2) in land area, in the U.S. state of Michigan. It is located in Lake Huron, at the eastern end of the Straits of Mackinac, between the state's Upper and Lower Peninsulas. The island was home to an Odawa settlement before European exploration began in the 17th century. It served a strategic position as a center on the commerce of the Great Lakes fur trade.

During the War of 1812, the British captured the fort in the Siege of Fort Mackinac, the first battle of the conflict, because the Americans had not yet heard that war had been declared. The victorious British attempted to protect their prize by building Fort George on the high ground behind Fort Mackinac. In 1814, the Americans and British fought a second battle on the north side of the island. The American second-in-command, Major Andrew Holmes, was killed and the Americans failed to recapture the island.  Despite this outcome, the Treaty of Ghent of 1815 forced the British to return the island and surrounding mainland to the U.S. The United States reoccupied Fort Mackinac, and renamed Fort George as Fort Holmes, after Major Holmes. Fort Mackinac remained under the control of the United States government until 1895 and provided volunteers to defend the Union during the American Civil War. The fort was used as a prison for three Confederate States of America sympathizers.  John Jacob Astor's American Fur Company was centered on Mackinac Island after the War of 1812 and exported beaver pelts for thirty years. By the middle of the 19th century, commercial fishing for common whitefish and lake trout began to replace the fur trade as the island's primary industry. As sport fishing became more popular in the 1880s, hotels and restaurants accommodated tourists coming by train or lake boat from Detroit.  Following the Civil War, the island became a popular tourist destination for residents of cities on the Great Lakes. Much of the federal land on Mackinac Island was designated as the second national park, Mackinac National Park, in 1875, just three years after Yellowstone National Park was named as the first national park. To accommodate an influx of tourists in the 1880s, the boat and railroad companies built hotels, including the Grand Hotel. Souvenir shops began to spring up as a way for island residents to profit from the tourists. Many wealthy business magnates built summer "cottages" along the island's bluffs for extended stays. When the federal government left the island in 1895, all of the federal land, including Fort Mackinac, was given to the state of Michigan and became Michigan's first state park. The Mackinac Island State Park Commission appointed to oversee the island has limited private development in the park and requires leaseholders to maintain the island's distinctive Victorian architecture.  Motor vehicles were restricted at the end of the 19th century because of concerns for the health and safety of the island's residents and horses after local carriage drivers complained that automobiles startled their horses. This ban continues to the present with exceptions only for emergency and construction vehicles.

Using a quote from the above article, answer the following question: Who was helping him
Fort Mackinac remained under the control of the United States government until 1895 and provided volunteers to defend the Union during the American Civil War.