[1][2] In 1831, in the wake of Nat Turner's Rebellion in Southampton, when Gardiner was still a child, his was one of the families who relocated to Liberia under the sponsorship of the American Colonization Society.

In the same election, the True Whig Party won a massive victory and proceeded to dominate Liberian politics until a coup d'état in 1980 ended almost a century and a half of minority rule by the Americo-Liberians.

As president, Gardiner called for increased trade with and investment from outside countries, improved public education, and closer relations with Liberia's native peoples.

Rivalries between the Europeans colonizing West Africa and the interest of the United States helped preserve Liberian independence during this period, and until 1919, despite Liberia's ongoing disputes with England and France.

Liberia was drawn into a border conflict with the British Empire over the Gallinas territory, lying between the Sewa River and the Mano River—territory which now forms the extreme eastern part of Sierra Leone.