I found an article that mentions Simeon Gashwiler but 'Americanized' to "Gashwilder" in the article of Howard County, MO. He met the famous Clay Allison on a trail run of cattle. According to their story, this Clay Allison was a stranger, whom they hired to forage for the drive. The story took place in November 1869, but was told by one of the men (many who were from Howard Co MO) named Dan Silver. The men added their names as witnesses. The story goes that they were driving the cattle from Collen County, Texas and when the stopped at Deep Fork, a stream in Creek Nation. Clay was out foraging and came across a party of Osage indians that he later figured out when he returned to camp had stolen the mens horses. With the only horse, he heads back out to track down the thieves when he ends up in a fight with them. The men later testify that it was the single most brave act they ever saw. The men who witnessed it were:
Of Howard County: Dan Silver, Sim. Gashwilder, Dee Collins, Billie Dotie, Joe Nueves. Of Clifton Tenn: Billie McCully.

https://www.newspapers.com/article/chetopa-advance-clay-allison-fight-repor/2848098/