In its most basic form, the term “bullpen” refers to the physical location where the team’s relief pitchers warm up prior to entering the game. Typically, this area is a fenced-off section beyond the outfield fence, although occasionally it can be found in foul territory down the outfield lines. From here, this physical location has over time lent its name to two related terms. By metonymy — a figure of speech in which one thing takes on the name of something closely related to it — it has become the collective name for a team’s group of relief pitchers (for example, the Yankees’ bullpen). Additionally, because they often take place in the bullpen, the scheduled throwing that a starting pitcher does in between starts or that a rehabbing pitcher does as part of his rehab is often called a bullpen.
As baseball fans, we use the word “bullpen” all the time. But how did a word that sounds more like it belongs in a rodeo than on a baseball diamond find its way into the sport? Some speculate that it is in fact a reference to rodeos and dairy farms, suggesting that relief pitchers are like bulls ready to be released onto the field. Others say that advertisements for Bull Durham tobacco adorned early stadiums, often located near where the relievers warmed up. Casey Stengel infamously theorized that managers sent relievers away from the dugout because they got tired of them “shooting the bull” (a family-friendly euphemism) before they entered the game, while ESPN’s Jon Miller claimed that bulls were kept in a pen right beyond the fence in the early days of the Polo Grounds.
All of these are nice theories which sound fairly plausible. As any good Classicist would tell you, however, once you have several theories like this floating around about the etymology of a word, there’s a good chance that none of them are correct. In fact, each theory likely represents a later attempt at making sense of a term that on the surface just does not fit in the slightest.
What do we know? Well, the first recorded use of the term “bullpen” in a baseball setting dates back to May 7, 1877, when O.P. Caylor made the following off-hand remark in a game recap for The Cincinnati Enquirer:
The bull-pen at the Cincinnati grounds with its `three for a quarter crowd’ has lost its usefulness. The bleacher boards just north of the old pavilion now holds the cheap crowd, which comes in at the end of the first inning on a discount.
As can be seen here, the bullpen was not originally the place where pitchers warmed up, but rather a spot — given the small size of 19th-century ballparks, presumably next to the foul lines — where teams essentially sold “standing room only” tickets. Later on, when the concept of relief pitchers took hold and a place for them to warm up was needed, they converted these areas to what we think of when we hear the word “bullpen.”
Now we’ve got a terminus ante quem (latest possible date) for the term in a baseball setting. But how did a standing room only section receive this name? To get an idea, we must ask ourselves the question, “Where else was the word used during the late 19th century?”
The answer lies in Coeur d’Alene, Idaho, in the year 1899. For a decade, union miners were frustrated by wage cuts, moles hired by management to infiltrate and spy on the union, repeated military occupation of the mines at the request of management, and regular attempts to break the union. In 1899, tensions spilled over, resulting in a dynamite attack on a non-union mining facility, the torching of several homes and offices, and two murders. In response to the violence, Idaho’s governor Frank Steunenberg sent in the military and ordered mass, indiscriminate arrests of the region’s male population, regardless of whether or not they worked in the mines. Those rounded up were placed in a makeshift prison made up of hay-filled barns and abandoned train cars. This prison, known for its barbaric conditions that were meant to discourage later attempts at unionization, was called “the bullpen.”
At this point, we have two different contexts in which the word “bullpen” was used, and in truth, there is a similarity between the two: both instances describe an area used to hold a large group of people (the difference being, of course, one held paying customers, the other political prisoners arrested by the army). And there’s only one place in the 19th century where baseball and the army overlapped: the Civil War.
For the first few years of the Civil War, both the Union and the Confederacy engaged in a prisoner exchange that in essence allowed prisoners of war to return to their families soon after being captured, primarily on the condition that they not return to the military upon their release. This setup was designed to eliminate the need to house large amounts of POWs. The system collapsed in 1863, however, because the Confederacy began to classify black soldiers as fugitive slaves that needed to be returned; the Union in turn refused to return prisoners until the South treated black and white soldiers equally.
The soaring number of prisoners led to the construction of large prison camps, such as Camp Sumter in Andersonville, Georgia. Conditions in the prison, run by Confederate commandant Henry Wirz, were horrendous even by the standards of the day. As John E. Warren, a Union soldier who spent 162 days at Andersonville, wrote:
The prison pen, or bull pen, as it was commonly called by its occupants, contained at this time about twenty-four acres, at least one third of which was swamp, almost impassable, much less habitable...The number who occupied the pen at this time could not have been less than 30,000, and this was constantly increasing.
Not surprisingly, disease and starvation were rampant, and as many as one-third of the 45,000 prisoners who wound up at the camp did not leave it. Because of this, Wirz became just one of the two men to be executed for war crimes committed during the war, although that is a story for a different day.
From here, we can start to theorize a bit about how “bullpen” found its way into baseball. Chances are, most soldiers who fought in the war had some concept of what “the bull pen” was, even if they never actually found themselves near one. They would have brought this slang term home from the front with them, applying it to any situation that would have involved a large number of people crowded in a very small area.
It’s no small stretch to believe that the section marked off for standing room only at events would have readily elicited comparisons to the Civil War prison camps — after all, many children’s games, such as Capture the Flag, often use military and prison imagery. Over time, as the sport of baseball evolved to require more pitchers and its popularity grew to require more seating, the standing room only section was kicked out of the bullpen and sent to the areas that would later become the bleachers. The location’s name, however, did not follow the fans, and eventually, the term’s original use was forgotten.