The Stockade had been secured to prevent its falling, even if undermined.

He said, in addition, that Sherman had been badly defeated by Johnston, and driven back across the river, so that any hopes of co-operation by him would be ill-founded.
When the Sergeants returned, he caused the following notice to be posted on the gates: NOTICE.
Not wishing to shed the blood of hundreds, not connected with those who concocted a mad plan to force the Stockade, and make in this way their escape, I hereby warn the leaders and those who formed themselves into a band to carry out this, that I am in possession of all the facts, and have made my dispositions accordingly, so as to frustrate it.

No choice would be left me but to open with grape and canister on the Stockade, and what effect this would have, in this densely crowded place, need not be told.
May 25,1864.
H.Wirz.
The next day a line of tall poles, bearing white flags, were put up at some little distance from the Dead Line, and a notice was read to us at roll call that if, except at roll call, any gathering exceeding one hundred was observed, closer the Stockade than these poles, the guns would open with grape and canister without warning.
The number of deaths in the Stockade in May was seven hundred and eight, about as many as had been killed in Sherman's army during the same time..