The Cosmopolitan Arms Co. was established by Edward Gwyn and Abner Campbell in 1859 in Hamilton, Ohio.  One-of-a-kind breechloading rifles and carbines known as the Cosmopolitan, Union or Gwyn & Campbell Carbines, were manufactured using variations following  Gwyn's previous business partner, Henry Gross's 1859 patent and by Gwyn's own patent #36, 709 in October of 1862.  They manufactured the Cosmopolitan production-type, transitional production type Cosmopolitans, Gwyn & Campbell Type I Long Sight Model, Type I Short Sight Model, Type II First Model, Type II 2nd Model and the Type II 3rd Model for use during the Civil War.

When the company was in full production in their third factory, they were reported to be employing 125 men.  Hamilton's population was a little more than 7,000, making them one of the largest employers at that time.

The following regiments were supplied with arms from the Cosmopolitan Arms Company: 2nd & 3rd Arkansas; 5th, 6th & 16th Illinois; 3rd & 4th Indiana; 4th & 8th Iowa; 2nd, 6th & 14th Kansas; 10th, 12th, 14th & 40th Kentucky; 4th & 8th Missouri; 5th & 8th Ohio; 7th Tennessee; 3rd Wisconsin.   

Henry Gross (Jr.) was born in Juniata County, Pennsylvania, July 21, 1813, and moved with his father Henry Gross, Sr. to Tiffin, Ohio, in 1831.  He was an active gunsmith and inventor and in the gunsmith, clock and watch business through the decade of the 1860's.  Rentschler states in his book that since evidence is lacking, he speculates that Gross and Campbell met in Tiffin, Ohio, combined their efforts, then separated after a business failure.  Gross continued making guns and secured patent #39, 479 in August of 1863 for his breechloading gun.  During the 1870's, Gross was employed at Hall Safe and Lock Co. in Cincinnati.  His death date is uncertain, somewhere between 1875-1880.

Edward Gwyn was born May 12, 1816, at St. James Parish, London, England.  He first came to the U.S. in 1842 and worked for a gas works in New York City.  Gwyn reportedly didn't like New York, so he left for Spain, where his wife was born, and returned to the U.S. in the early 1850's.  After creating the Tiffin Gas Works in Tiffin, Ohio, with his brother, John, Gwyn established a gas works in Lafayette, Indiana, about 1852, and then the Hamilton Gas Light and Coke Company in Hamilton, Ohio in 1855, and the gas company in Springfield, Ohio, in the late 1860's.  During this time, he was also an independent machine tool salesman, sometimes traveling to Europe.  On May 25, 1879, on a business trip to the Netherlands, Gwyn died.  He is buried in Springfield, Ohio.

Abner Caruthers Campbell was born in Hamilton, Ohio, July 12, 1824, part of a prominent Ohio family.  His brother, Lewis D. Campbell and nephew, James E. Campbell, would become active in the Republican party in the second half of the 1800's.  Lewis would become a Colonel in the Civil War, later a U.S. Congressman, and then Minister to Mexico.  James, a Civil War Naval Masters Mate, was elected Governor of Ohio in 1889.  Abner was a partner with Gwyn in the Hamitlon Gas Light and Coke Company and also in the Cosmopolitan Arms Co.  Primarily, Abner was the operator and the principal owner, along with this brothers, father-in-law, and others in a major lumber, mill-work, and coal business.  Campbell died in 1868 and is buried at Greenwood Cemetery in Hamilton, Ohio.

Source material from Thomas B. Rentschler's book, "Cosmopolitan and Gwyn & Campbell Carbines in the Civil War."