Six Weapons Used for the First Time in the U.S. Civil War   Weapon Notes 1 Machine gun machine gun is defined as a gun that fires rapidly and repeatedly 2 Landmine developed by Confederate Brig. Gen Gabriel Rains in 1862 3 Observation balloon both Union and Confederate forces experimented with balloons 4 Anti-balloon gun   5 Repeating rifle   6 Mounted railroad cannon the most famous one was called the Dictator Content provided by: Larry Gormley, HistoryShots Source(s): Historical Times Illustrarted Encyclopedia of the Civil War The Civil War Book of Lists, by the editors of Combined Books