James R. Rummel of Hell in a Handbasket has a post about early handgun bayonets. The Elgin Pistol Cutlass (above) was a single-shot pistol available in the U.S. in various calibers starting in the 1830s. It's basically a built-in machete that served to clear away brush while tramping out in the wilderness:
Instead the guns were designed to be used as brush cutters in dangerous territory. The heavy knife would clear away the jungle, while the pistol would be ready if enraged animals or hostile natives suddenly sprang from the bracken.
At the link, you can view pictures of a bayonet that could be fitted onto World War I-era British revolvers.
http://hellinahandbasket.net/?p=4828 | Photo: American Firearms
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The first fifty Elgin pistols we have on record were ordered for the US Exploring Expedition of 1837. The journals and letters that were written by the members of the expedition are pretty specific as to the purpose of the blade as a means to make trail through heavy brush.
Twenty-five years later, those very same pistols were issued to Union sailors on blockade duty during the American Civil War, and they were supposed to be used as a weapon while boarding enemy vessels. The official records note that the guns were "unpopular" with the men, which probably means that they were hated with a passion so intense we can barely understand it.
The Elgin was quickly replaced with the M1860 cutlass, which proved to be "popular". We can only speculate as to the relief that some enlisted schmoe felt when he was allowed to turn in his Elgin for a nice, heavy-bladed chopping sword.