Major Benjamin Henry Grierson led 1,700 men of the 6th Illinois Cavalry, some of whom would have been armed with the Cosmopolitan, on his successful raid into Mississippi to disrupt Confederate supply lines from April 17, 1863 to May 2, 1863.2 Grierson reported that “they destroyed 60 miles of railroad, captured 3,000 arms, took an ‘immense’ amount of supplies, captured 1,000 horses and mules, killed and wounded about 100 of the “enemy,” captured and paroled over 500 men, including many officers, and he estimated they drew approximately 38,000 troops away from Vicksburg.”3 Although Grierson may have exaggerated some of the numbers as officers in the Civil War sometimes tended to do, the raid was an important step in the war, and helped Grant in the Battle of Vicksburg.3 Although the Union Carbine was not the preferred weapon, many troops seemed to be thankful to have a breech-loading carbine, and it sufficed until better carbines came available.

​
The Fifth Illinois demonstrated much of the same pattern, with the “Cosmopolitan” Carbines being slowly replaced by Sharps. In the fourth quarter of 1862, the regiment was issued 306 Cosmopolitans, then that number peaked in the second quarter of 1863, and finally slowly declined. From the second quarter of 1864 to that year’s third quarter, the number of Cosmopolitans dropped from 247 to 3.4 The trend in these regiments demonstrated how the advancing technology and increased durability of arms slowly took precedent in military ordnance once supply was able to catch up to a degree with demand. Although the Union carbine played a significant role, its advancements accompanied by its flaws were no match for the innovative Sharps and especially the Spencer. When new arms were available, the Union carbines were replaced.