Where in 'The Count of Monte Cristo' does physical combat take place and with whom?"The Count of Monte Cristo" by Alexandre Dumas

In a secret drawer of Monsieur Noitier is a recording of physical violence.  After the death of the Marquis and Marquise de Saint-Meran, Monsieur de Villefort puts into execution the Marquise's last wishes.  Valentine is sent for as he expects M. d'Epinay, his two witnesses and the notary in order to arrange the marriage of his daughter.

However, M. Noitier has other plans.  When the notary arrives, he informs M. d'Epinay that M. Noitier has disinherited her entirely. This having been said,  M. Noitier sends word that he wishes to speak to the Baron d'Epinay. After Valentine and the baron arrive with M. de Villefort, the servant Barrois is instructed to pull from a secret drawer papers that reveal the history of the grandfather of Franz d'Epinay, the proposed fiancee of Valentine. 

A General de Quesnel was invited to a meeting with men loyal to Bonaparte.  Word had it that the general, too, was so devoted; however when questioned, it was discovered that this man was loyal to the monarchy and possibly a spy.  He had attempted to use his own coachman, and to peek under the required blindfold.  Upon his arrival, General de Quesnel declared his loyalty to Louis XVIII.  The President of the Bonapartist Club tells the general,

We have ben acting under a misapprehension; for the sake of promotion and a title, you have thrown in your lot with the new Government , a Government we would overthrow....Now, you understand, it would be too convenient for you to put on a mask to aid you in learning the secret of others and then have nothing further to do than remove the mask to ruin those who put their trust in you.  Uou must tell us quite whether you stand for the king of the moment...or His Majesty, the Emperor.

Because the general declared, "I am a Royalist," he was told  to swear an oath that he would not reveal anyone or anything.  As they prepared to take him home, General Quesnal insulted the President, and he "refused to go a step further without honourable reparation."  The two men travel to the Quai des Ormes and step out of the carriage.

The President and General Quesnel duel; both are wounded in at least three places, but the general is wounded mortally.  Valentine shrinks back, for many a time she has seen the  marks of two sword wounds on her grandfather's arm.  The President was none other than M. Noirtier.  At this knowledge, Franz "sank lifeless into a chair."