In the six months following the start of the spring campaign of 1864, a titanic struggle ensued between Ulysses S. Grant commanding the Army of the Potomac and Robert E. Lee commanding the Army of Northern Virginia. During that time Grant suffered over 50,000 casualties – more than the size of Lee’s entire army. Such astronomical casualty figures virtually guaranteed that Lincoln would pay the ultimate price during that presidential election year. On August 23, 1864 Lincoln wrote the following: 'This morning, as for some days past, it seems exceedingly probable that this Administration will not be re-elected. Then it will be my duty to so cooperate with the president-elect, as to save the Union between the election and the inauguration; as he will have secured his election on such ground that he can not possibly save it afterwards.'