Vicksburg: manoeuvre enabled by the Mississippi

Vicksburg and the Meridian campaign were precedents for the march. The Vicksburg operation bypassed strong Confederate positions and forced their defenders into a less favourable fight. Its objective was control of the Mississippi and access to lower-river supply routes. David Dixon Porter's fleet carried logistics and heavy weapons that Grant's land forces could not sustain independently. Losses are given as nearly 40,000 Confederates, including surrenders, against about 10,000 Union troops, although estimates of the starting strengths differ sharply. Once the river was open, Union mobility became a lasting operational advantage rather than a temporary raid behind enemy lines.