Final answer:
The policy requiring all Jamestown colonists to work was the most crucial action taken by Captain John Smith, as it directly addressed the colony's need for self-sufficiency and stability during critical times.
Step-by-step explanation:
Of the instrumental actions taken by Captain John Smith for the survival of the Jamestown Colony, the enforcement of a policy requiring everyone to work, which coupled the principle ‘those who did not work would not eat’, can be considered the most essential. By mandating hard work among all colonists, including the gentlemen, he ensured that the settlement focused on the essentials: obtaining food, improving shelter, and enhancing security.
This policy fostered self-sufficiency, pulling the colony back from the brink during the ‘starving time’ and set the foundation for eventual stability and growth, which was especially important given that the colony had to overcome issues like poor leadership, supply shortages, and conflicts with the Powhatan.