Entering Illinois College in 1840, I found the word further transformed. The first syllable only was used in our game of "bull-pen," called also "sock-ball." Four players, among whom a ball was passed from hand to hand, stood at the corners of a square of about fifty feet; inside the square four other players danced about, who must dodge the swift balls sent at them by the players on the corners when these thought that they could score a hit. The phrases "sock him" and "sock it to him" were used.-The Dial, Volume XXXII (1902)
This comes from a letter, written by Samuel Willard, that appeared in The Dial in 1902 and there are several things of interest here. First, Willard was actually writing in regards to the etymology of the word "sock" and its development from the word "sockdologer." The other things that are important in the letter relate to the ball-playing culture that existed in central Illinois in the forty years prior to the Civil War.
Bull-pen was a game that appears to have been very popular in central Illinois in that period and most likely was the most popular and most played ball game in the area, especially among school children. It is mentioned time and again in memoirs and histories. Willard is just one more reference to a game that we already know a good deal about, although his letter does contain a nice description of the game. However, this is the first reference I've seen equating bull-pen with sockball. Sockball was mentioned by name in Henry Philpott's article A Little Boy's Game With A Ball, published in 1890, but I think this is the only reference we have to the term being applied to a game played in Illinois. Actually, Willard and Philpott are the only two references I know of that mention a game called sockball but I haven't really looked at it too closely.
Another interesting thing is the fact that this game was played at Illinois College, which is located in Jacksonville, Illinois. The Social Order of a Frontier Community, a book which has influenced my thinking with regards to the spread of bat and ball games in United States, is, essentially, a social history of Jacksonville from 1825 to 1870 and Illinois College and its students play an important part in that story. Don Harrison Doyle, the book's author, doesn't mention baseball or town ball or sockball or anything like that in what is really a fantastic book but his ideas about how frontier communities developed during the antebellum era and how they structured themselves in a search for stability and order in a very chaotic world gave me a lot of ideas about the role ball games played in the development of frontier society. I find it ironic that I found a reference to ball-playing in the town that Doyle used to illustrate his thinking about frontier society.