looks like they were out of grass. Not much prairie here any longer but I still rent some ground on the huzzah prairie. There's a real nice spring there. Interesting reading to me.
https://www.nps.gov/buff/learn/historyculture/richland-creek-may-1864.htm
https://www.nps.gov/buff/learn/historyculture/richland-creek-may-1864.htm