7-102. Just as there is a relationship between unit size and the ability of a friendly force to execute a turning movement instead of an envelopment, this relationship extends downward between an envelopment and a flank attack. Corps and divisions are the most likely echelons to conduct turning movements. Divisions and BCTs are the echelons most likely to conduct envelopments—single or double. Smaller-sized tactical units, such as maneuver battalions, companies, and platoons, are more likely to conduct flank attacks than larger tactical units. This is largely a result of troop-to-space ratios and sustainment and mission command constraints. The Confederate attack by the four divisions of Stonewall Jackson’s II Corps of the Army of Northern Virginia on the Union XI Corps of the Army of the Potomac at Chancellorsville on 2 May 1863 is a historical example of a flank attack.