Today, the 19th Century Age of Imperialism seems a quaint anachronism – an era populated by a new wave of technological marvels. Imperial ambition burst beyond the limits of Earth and soon included the Moon, Mars, Venus, and Mercury as stages upon which these contests were played out. This lecture surveys the figures, powers, events, and technologies of the era, ending as the stage was set for the interplanetary struggles of the 20th Century.