The Colonization Fleet

To guarantee the success of a Manned Colonization mission we must send a fleet of space ships. Wernher von Braun envisioned a fleet of ten spacecraft . The exploration of mars could be done with a couple of ships, but the colonization of mars will require more than half a dozen people.

 

Wernher von Braun also worked out preliminary concepts for a manned Mars mission which used the space station as a staging point. His initial plans, published in The Mars Project (1952), had envisaged a fleet of ten spacecraft (each with a mass of 3,720 metric tons), three of them unmanned and each carrying one 200-ton winged lander^[29] in addition to cargo, and nine crew vehicles transporting a total of 70 astronauts. Gigantic as this mission plan was, its engineering and astronautical parameters were thoroughly calculated. A later project was much more modest, using only one purely orbital cargo ship and one crewed craft. In each case, the expedition would use minimum-energy Hohmann transfer orbits for its trips to Mars and back to Earth.   from Wikipedia

The Mars Project,  By Wernher Von Braun, Henry J. White (The book on google)