Richard Bak's 1998 book, "A Place for Summer: A Narrative History of Tiger Stadium" has the full story. In the 19th century, the city of Detroit had a military unit called the Detroit Light Guard, who were known as "The Tigers". They had played significant roles in certain Civil War battles and in the Spanish–American War. The baseball team was called both the "Wolverines" and the "Tigers" in the newspapers. Upon entry into the major leagues in 1901, the ballclub sought and received formal permission from the Light Guard to use its trademark, and from that day forth the team has been officially the "Tigers". Certainly when the team started major-league play in 1901, they were already wearing a tiger logo on their caps.