Web Author's Notes:
This map shows good detail on the location of the different organizations and units at Vicksburg during the First Assault. The 16th Ohio was near the southern end of the Union assault line under Col. Daniel Lindsey's 2nd Brigade under Gen. Peter Osterhaus' Ninth Division reporting to Maj. Gen. Edward Ord, commander of the 13th Army Corps.Gen.

Ulysses Grant's forces had just come from the Battle of Big Black River Bridge (May 17) and were rapidly pursuing the Rebels back into Vicksburg. The First Assault was less organized and concentrated than the Second Assault (May 22) to come, not all of Grant's troops having yet reached the Rebel fortifications. Grant was hoping the demoralized Confederate troops, under Gen. John Pemberton, would not be able to mount a viable defense in time to stop him from breaking through and taking the city.

Map by Hal Jespersen and obtained from Wikipedia.