I also recommend this video:
So we had not only a city and state divided but the baseball community in St. Louis was divided as well. Members of the baseball fraternity would go on to serve on both sides in the war. Some would be killed in action. Some would be taken prisoner. Some would become generals. But in May of 1861, these men were pointing guns at each other in St. Louis. Men who the previous year had taken part in some of the earliest baseball games ever played in the city were now willing to fight and kill each other. People - men, women and children - died in St. Louis on May 10, 1861, and some of our pioneer ballplayers were in the middle of all of that.