The dramatic story of the most famous regiment in American history: the Rough Riders, a motley group of soldiers led by Theodore Roosevelt, whose daring exploits marked the beginning of American imperialism in the 20th century.

When America declared war on Spain in 1898, the US Army had just 26,000 men, spread around the country—hardly an army at all. In desperation, the Rough Riders were born. A unique group of volunteers, ranging from Ivy League athletes to Arizona cowboys and led by Theodore Roosevelt, they helped secure victory in Cuba in a series of gripping, bloody fights across the island. Roosevelt called their charge in the Battle of San Juan Hill his “crowded hour”—a turning point in his life, one that led directly to the White House. “The instant I received the order,” wrote Roosevelt, “I sprang on my horse and then my ‘crowded hour’ began.” As The Crowded Hour reveals, it was a turning point for America as well, uniting the country and ushering in a new era of global power.