3. Battles have multiple names because the of the backgrounds of their soldiers.

The bulk of the Union troops were city dwellers and townspeople. When they talked about a battle, the notable things they saw were the natural features of the battlefield. Confederates were by and large from rural areas.

When they remember a battle, their inclination is to talk about the manufactured, populated, or otherwise man-made features of the area.

For example, both times the two forces met near Manassas Rail Station, the Southerners dubbed the fights First and Second Battle of Manassas, while the Union troops named it after Bull Run, the nearby stream. At least 230 such Civil War combat actions are known to have multiple names.