What kind of military existed during the Industrial Revolution?

The Industrial Revolution in the United States began in the early 1800s and ended around 1840.  The next thirty years are categorized as the Second Industrial Revolution, in which steam power revolutionized transportation and machinery.  It was during the Second Industrial Revolution that the Civil War occurred.

The War of 1812, the First Seminole War, and the Second Seminole War all occurred during the time period between 1800 and 1840 (though the Second Seminole War continued on after 1840).  There were smaller wars and battles fought, as well.

At this time in U.S. military history, only three branches were in existence.  The U.S. Army, Navy, and Marine Corps were all officially established within a fifteen year time period in the late 1700s.  These were the only branches of the military during time of the Industrial Revolution.  The time period of the Industrial Revolution was a time of relative peace for the United States.