It may be an obsolete object in terms of wars, but the Caissons name holds a special place in military culture.
If you want to go with literal meanings, the athletes at
Fishburne Military (Waynesboro, Va.) can't really move anywhere without a horse. But don't go with the literal meaning, because we know that the Caissons are out there competing in sports, so they are far from obsolete.

Photo courtesy of The Curtis Initiative
A caisson is "
a usually 2-wheeled vehicle for artillery ammunition attachable to a horse-drawn limber" according to the Merriam-Webster Dictionary, and that obviously is more applicable to wars fought long ago. It's not too wise to go to war with a caisson these days.
The caisson played a major role in the armed forces, and the name plays a huge role in the official anthem of the United States Army. Back in 1908 First Lieutenant [later
Brigadier General] Edmund L. Gruber wrote "The Caisson Song" while stationed in the Philippines, and in 1917 the song was changed to a march and renamed the "Field Artillery Song." Then in 1953,
it evolved into its current form: "The Army Goes Rolling Along."It's definitely a nod to history, and it's definitely a word that is fading in usage - as now the word applies to a certain type of casing in architecture and engineering.
So even though the school's mascot name is one that most people have no clue what it means, it hardly means that Caissons is a name that shouldn't be considered one of the nation's best. The school has existed since 1879 and takes pride in a mascot name that nobody else in America has - one that is lethal and perfectly applicable.