Like many things in the United States the great dividing line was the Civil War. The country and its government changed dramatically over the four years of the war. From culture to industry the changes in the nation were dramatic.
Slavery was ended which changed the the entire economic and social structure of the American South. The cities of the North became the homes of millions of immigrants, many of whom fought in the war for the Union. The North, at first, and then the South became industrialized changing the United States from a rural country to an industrial one.
One of the major changes was the one that took place in the United States Navy. The changes were so dramatic and widespread that an antebellum sailor would not recognize the post-war Navy. Our naval forces to this day reflect the changes and will for decades to come.
The antebellum United States Navy was a small force of wooden sailing ships that patrolled the trade routes used by major American commerce ships. Some ships had steam paddle wheels that enabled them to sail a steady speed when wind was not available.
In 1843 the United States launched the U.S.S. Princeton the first propeller-driven ship in the world. The Princeton was driven by a steam engine. The ship was designed by John Ericcsson, a Swedish immigrant. He also designed the revolutionary propeller which he called a screw.
But when the secretary of state and the secretary of the Navy were both killed by an exploding gun during a public relations cruise the following year Ericcsson was blamed despite having nothing to do with the invention of the gun. He was shut out of further contracts with the Navy until the Civil War.
In the 1850s the United States embarked on a ship-building program that focused on building steam-driven vessels called screw frigates. In 1855 the first of the screw frigates, the U.S.S. Merrimack, was launched. It was 257 feet long, displaced 3,200 tons and carried 50 guns. But the Merrimack-class was not quite as revolutionary as was believed. They still carried three masts and the full rigging of sailing-era ships and with 23-feet of draft there were a number of ports that they were unable to enter. A total of six ships of this class were built.
They were followed by another class of screw frigates, the Hartford-class. These were the first of the twin-screw frigates. They were somewhat smaller than the Merrimacks and had a draft of 18 feet enabling them to enter virtually every port in the United States. The U.S.S. Hartford was followed by the Richmond, the Brooklyn, the Pensacola and the Lancaster.
The Hartford-class was followed by yet another class of screw frigate. The first of this class was the U.S.S. Mohican which was launched in 1859. The five subsequent ships of this class were named for Indian tribes. Even though they stilled carried masts and spars their sail pattern was much reduced. They were the first to be classified as genuine steam warships rather than auxiliary steamers. They were also the first to carried large caliber pivot guns rather that guns arrayed in broadside.
At the outbreak of the war the United States Navy had fewer than 90 warships. Of these only 42 were capable of active service. Most of these were around the world showing the flag from Brazil to China. When Lincoln asked his Navy Secretary Gideon Welles what ships could be made available for immediate service he could only name 12 ships. Much would need to be done to prepare the Navy for all of the tasks that would required of it in the forthcoming war.