He spent first ten years of his life in Virginia, United States, and then he was sent to his uncle, General Donald Graham, to finish school and prepare for West Point.

In 1860, McIver fought under Giuseppe Garibaldi in Italy, and after that joined the pretender for the Spanish crown, Don Carlos.

When the Confederacy capitulated, McIver fled to Mexico, where he joined Emperor Maximilian in fighting Juárez’s rebels.

When the Juárez rebellion was successful, Maximilian was executed, and McIver fled to Tampico, where he boarded a ship and left for South America.

In 1883, McIver organized a company for British colonization of New Guinea; the project had to be abandoned in 1884 after failing to gain the approval of the Earl of Derby.