 He fought at Monterrey, and for his deeds received the title of count.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 the War of 1877-1878, McIver offered his services to the Serbians, initially being commissioned a colonel of volunteers and later rising to the rank of general and overall cavalry commander of the Serbian contingents.