It helped discredit the expansionist policy of Manifest Destiny the Democratic Party had often supported.[120][121]
Pierce favored expansion and a substantial reorganization of the military. Secretary of War Davis and Navy Secretary James C. Dobbin found the Army and Navy in poor condition, with insufficient forces, a reluctance to adopt new technology, and inefficient management.[122] Under the Pierce administration, Commodore Matthew C. Perry visited Japan (a venture originally planned under Fillmore) in an effort to expand trade to the East. Perry wanted to encroach on Asia by force, but Pierce and Dobbin pushed him to remain diplomatic. Perry signed a modest trade treaty with the Japanese shogunate which was successfully ratified.[123][124] The 1856 launch of the USS Merrimac, one of six newly commissioned steam frigates, was one of Pierce's "most personally satisfying" days in office.[125]

Bleeding Kansas
Main articles: Kansas–Nebraska Act and Bleeding Kansas
The Kansas–Nebraska Act organized Kansas (in pink) and Nebraska Territory (yellow).
The greatest challenge to the country's equilibrium during the Pierce administration was the passage of the Kansas–Nebraska Act. 