This Day In History | Civil War July 30 1864 Battle of the Crater On this day, the Union's ingenious attempt to break the Confederate lines at Petersburg by blowing up a tunnel that had been dug under the Rebel trenches fails. Although the explosion created a gap in the Confederate defenses, a poorly planned Yankee attack wasted the effort and the result was an eight-month continuation of the siege. The bloody campaign between Union General Ulysses S. Grant and Confederate Robert E. Lee ground to a halt in mid-June, when the two armies dug in at Petersburg, south of...