Joan's captors would not let her attend church or confession even though they had promised she could - if she would only sign Cauchon's statement of faults. She was not turned over to the church, as she was told she would be. Instead, the English jailers (who actually slept in her cell) continued to taunt her with threats of rape.
Joan wore only women's clothing, as she had agreed, following her "confession." Unknown to her, however, Cauchon and the English were not finished with their treachery.
One morning, soon after she had signed the statement of faults, Joan could not find the clothing she had taken off the night before. Unknown to her, the three English guards had removed all her clothes while Joan slept. Only the forbidden clothes - her soldier's clothes - were left in her cell.
To no avail, Joan pleaded for her "permitted" clothes. She needed to relieve herself. The guards would not allow her to leave her bed until she was dressed. She put on the "forbidden" clothes. They were all she had.
Because wearing men's clothes continued to be a crime against the Church, and because Joan had already renounced her actions in wearing them, Joan was now in an extremely dangerous position. She may not have realized how perilous it was for her to wear soldier's clothes. But it was that technical issue which led to the final charge against her: Joan was charged as a relapsed heretic.