Fort Stevens is a Civil War-era fort (yes, Civil War–the only earthen fortification west of the Mississippi at the time). The idea was to guard the mouth of the Columbia River, not from Confederates, but from the British, while we decided who got to plant their flag on the San Juan Islands.
It’s named for Civil War general Isaac Stevens (who also happened to be a not-so-great governor of Washington) who, at the Battle of Chantilly, took up the regimental flag (the thing the enemy aims at) from a wounded color bearer and inspired his men to push the Confederates back, helping make the battle a draw instead of a Confederate victory. (He was shot through the temple and died instantly.)
The original Civil War earthworks had cast-iron, muzzle-loading cannons, some of which could shoot a 128-pound ball three miles.
The earthworks housed cannonballs and powder, plus a furnace to heat the cannonballs before shooting. It was surrounded by an eight-foot-deep moat, complete with a 60-foot-long drawbridge.
The new fort is nearby (new meaning World War II).
Just like Battery Russell, Fort Stevens took fire from a Japanese submarine in 1942, but the Japanese only managed to destroy the baseball field’s backstop.
Since the Civil War, troops have been housed just south of the earthworks. (I’m assuming these pads are the remnants of more recent troop homes.)