Mr. Gatling suggested to a friend that his gun was such a superior weapon that it would make large armies unnecessary, leading to fewer and less deadly battles. It clearly did not. Do we know what Mr. Gatling thought of his gun in later years?

I highly reccomend the book Mr. Gatling's Terrible Marvel by Julia Keller for more information on the subject.

Gatling initially felt very strongly that the gun would make war unnecessary by being too terrible. "It occured to me," he wrote to a friend in 1877, "that if I could invent a machine-a gun-which could by rapidity of fire, enable one man to do as much battle duty as a hundred, that it would, to a great extent, supersede the necessity of large armies, and consequently, exposure to battle and disease be greatly diminished." This was his goal from the beginning, and as we all know re: the history of the 19th century, that did not happen-battlefields have only increased in scale and scope since then.

People that marvel over the gatling gun (i'm one of them, hence why this book is sitting on my bookshelf) often forget that Gatling also had competition at the time, so he had to actually market the gun. He pushed it aggressively as a humanitarian measure and was selling the gun to anyone who could by it, with guns like the famous 'potato-digger' being his direct competition. He also wanted to end the civil war and started his factory in Cincinatti to bolster the war effort, but production pretty much didn't have time to get in motion before Appomatox. His biggest early contracts were to the navy; the Navy found it useful for shipboard defense, but police departments, private individuals and the US Marines found use for them in specialized roles.

In later letters and newspaper articles it becomes less clear, and Gatling sometimes expressed regret or defensiveness about the gun and the uses it had been put to. By then it had been used for a healthy dose of imperialism and class warfare-Keller describes it being used by police unions to bust up striking crowds of workers. It didn't make warfare less terrible, it was making oppression easier and more efficient, but he was always ready to argue that this wasn't his intention when inventing the gun. He wanted to reduce the scale and scope of carnage, not make it easier to suppress natives and striking workers.

Overall it is a complicated subject, because how he truly felt about the invention in his private moments cannot be said and it is clear he was aware of it's misuse, but also proud of his invention and glad to have the royalties. One must remember that he clearly had to market the gun, but getting defensive about things like that in later articles means he was at least tangentially aware that it had failed in it's original intent. Gatling held a number of other really interesting patents in more mundane things like steamship propellers, but his name is always associated with the gatling gun.