The echelon formation was used to protect any exposed flanksagainst the enemy's possible attempt take advantage of thatexposure or should the enemy attempt to outflank the opposing enemyflank. This meant that separate units, the echelon units, wereseparated from the main army to form a protective body of troopspositioned 200 to 300 yards to either the rear, left or rightflanking movements of their own army. This formation was used byUnion General David Sickles during the 1864 Atlanta campaign.