Pardon the intrusion, but "O.R." series 1, vol. 53, pp. 455-8 contains the report on this fight by Major Richard G. Ward of the First Kansas Colored Infantry. In that report on page 456 he states:
"Shortly after crossing the stream we were made aware of the presence of the enemy in force by their scouts and by information from citizens who stated that Cockrell, Campbell, Hancock, and Turman had concentrated their forces on Osage Isand, and that their combined force amounted to some 700 to 800 men, all spendidly mounted."
I would assess that this included Colonel Vardaman Cockrell of Johnson County leading his summer's recruits to the southern army in Arkansas at the conclusion of the Missouri recruiting season. There is other evidence of his recruiting in the Johnson and Lafayette County area earlier.
"Turman" is Captain Bill Turman or Truman who operated in that area around Bates County that season. I assume his men were guiding the others through this neighborhood.
I draw a blank of the identity of "Campbell," but perhaps someone else may know him.
As for "Hancock" other sources identify him as the local Captain Bill Hancock who worked with Captain Bob Marchbanks in the Bates County and north Vernon County area. In early August he operated with Marchbanks in west Henry County according to "O.R." series 1, vol. 22, part 1, p. 544.
Toward the end of this fight in early November Quantrill's and Denverite Charles Harrison's bands rode through this same neighborhood together, so the northerners were fortunate they wrapped up the contest before those men came along.
I hope that helps.