Baldwin joined the U.S. Army Signal Corps the following year as a sergeant, piloting and maintaining their demonstration balloon.

In 1898, during the Spanish-American War, Baldwin was the pilot of the hot air balloon that gave U.S. troops location information of Spanish snipers before the Battle of San Juan Hill.

[2]: 194 From 1890 to 1907, Baldwin spent many summers at Denver's Elitch Gardens amusement park, where he made balloon ascents on Saturdays and Sundays, sometimes performing stunts on a trapeze as he ascended.

I must confess there were some apprehensive gasps as the starting whistle blew, but our fears soon gave place to a feeling of power and security as we ascended... From the great height of fifteen hundred feet, all Denver and its environs of mountains and plains lay spread before our entranced vision.

He celebrated his eighty-second birthday by tightrope walking 125 feet above South Boulder Creek, a crossing he'd made 80 times in 40 years.