Gatling filed in 1862 a patent for a weapon more rotary cannons. She initially used paper cartridges that limit its reliability. The tests are impressive nonetheless the US Army buys several models in 1865. In 1866, it is modified to fire ammunition brass case.
During the Civil War, the Gatling is not yet in official use in the Union army, but a few copies, purchased with private funds, however, are used. Two of these weapons were used in the siege of Petersburg and eight gunboats were deployed.
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