"It is hard on our men held in Southern prisons not to exchange them, but it is humanity to those left in the ranks to fight our battles. Every man we hold, when released on parole or otherwise, becomes an active soldier against us at once either directly or indirectly. If we commence a system of exchange which liberates all prisoners taken, we will have to fight on until the whole South is exterminated. If we hold those caught they amount to no more than dead men. At this particular time to release all rebel prisoners North would insure Sherman's defeat and would compromise our safety here." – General Ulysses S. Grant, August 18, 1864.
This quote from General Grant is often cited as evidence that he stopped prisoner exchanges and that he did it because of the callous arithmetic of the war – calculating that by stopping exchanges the Union armies could simply outlast the Confederates. His statement is so ingrained into the common interpretation of Civil War prisons that it was engraved on the Wirz Monument in the town of Andersonville. However, the prisoner exchange issue was far more complicated, and the timeline of exchanges does not support the notion that Grant stopped the prisoner exchange.