This article examines Captain Scott’s arrangement, announced on 3 January 1912, to add a fifth man to his Polar Party. Although it has been characterised as impulsive and ill-judged, primary expedition records suggest strategic and tactical rationales. Scott was deeply concerned about the physical hardship of prolonged travel on the Polar Plateau and sought to minimise exposure time. He also had a newly emerged tactical problem: the last support party could no longer keep up and might soon fail completely. Adding a fifth man would increase pulling power, allowing early release of the last support party; it would reduce time spent on the Polar Plateau, and it would provide a safety margin for worsening surface conditions. Secondary literature has focused on drawbacks such as tent crowding, increased cooking time, and ration redistribution. Such concerns are not strongly supported by primary sources, as many originate from the influential accounts of Apsley Cherry-Garrard and Roland Huntford, both of whom emphasised drawbacks while overlooking Scott’s underlying rationale. Drawing on diaries, letters, and contemporary records, this article argues that Scott’s fifth-man arrangement was a considered response to strategic and tactical issues at the time.