The trial of Louis Capet (as the deposed Louis XVI was called) began on December 11, 1792. He faced 11 charges, including having tried to prevent the meeting of the Estates-General and, in so doing, of having made an attempt upon liberty; having ordered the storage of grain, sugar and coffee; having made an agreement with Leopold II and the King of Prussia to restore the French monarchy; and having suspended the execution of a decree against the refractory priests. Louis retaliated to each of the charges and sought to give weight to his arguments. Even if he knew that his fate was sealed and that there was little he could do to prevent it, he was not resigned to it.
On January 15, the National Convention declared Louis Capet guilty of conspiracy against public freedom. 691 deputies voted "yea" in favor of a verdict of guilty; not a single deputy voted "nay". Sentencing would proceed over the following two days, with the main point of debate being whether Louis should be imprisoned, exiled, or put to death - and if it were to be execution, should the sentence be carried out immediately, or held in abayance until a more politically opportune time. In the end, immediate execution carried the day with 361 votes: the exact number needed for a majority.*
* It's almost like it was planned that way.