During Preston's tenure in that office, the United States Navy acquired new duties in the course of America's westward expansion and acquisition of California.

Trade and commerce in the Pacific Ocean beckoned, and the Stars and Stripes flew from the masts of Navy ships in Chinese waters, while the shores of Japan, then unopened to the west, presented a tantalizing possibility for commercial intercourse.

The Navy also was progressing through a technological transition, especially in the area of moving from sails to steam propulsion, and with the improvements in gunnery and naval ordnance.

Resuming his private law practice, Preston acquired a reputation for being a fine defense lawyer before being sent to France in 1858 to negotiate for the establishment of a line of commercial steamers to operate between Le Havre and Norfolk.

As the Confederacy was established and the United States divided into two hostile camps, both sides moved steadily toward open conflict.

Finding the President firm in his resolve to hold the Federal forts in the South, the three men returned to Richmond on April 15.

With the news of the firing on Fort Sumter in South Carolina on April 12, 1861, conservative and moderate strength in the secessionist convention melted away.