At the Last Supper, Jesus predicted the disciples would all fall away, even Peter. Peter, as the leader of the disciples, denies this vehemently! Jesus declares to Peter that not only will he deny him, he will do so three times before the night is out! Jesus says Peter would disown him in only a few hours, not dawn. Westerners miss this since we start the day at midnight and usually associate a rooster crowing with dawn. The rooster was used to mark the changes in watches during the night, thus it is only a few hours until Jesus is arrested.
Peter’s statement might be a reaction to a ‘slur” on his loyalty. Peter is willing to fight to defend the Lord, he is ready to be killed defending the Lord, he is completely loyal. Remember Peter is the first disciple to grasp who Jesus was, in Mark 8 it was Peter who declared that Jesus is the Christ, the Son of the Living God. Even though at that time he understood properly, he does not understand here that the Messiah was going to suffer and die, he will defend the Lord, and die by his side. But that is not the plan, the Messiah is to be abandoned. Peter is speaking as a representative of the disciples, after he speaks, all the disciples join in with him in declaring their loyalty.
Yet when the time for action arrives, Peter does attempt to defend Jesus and wounds a servant (John 18:8-11). When the soldiers arrive to arrest Jesus, Peter attacks the servant of the High Priest, cutting off his ear with a short dagger (μάχαιρα). This servant, Malchus, is named in John’s Gospel, although he is unknown to us. The name appears in inscriptions, although almost exclusively for Gentiles and Nabatean Arabs (BDAG).
Why attack the servant of the High Priest? It is possible he was leading the group to the garden to arrest Jesus. Malchus was not a slave carrying a torch for the people in charge, he was the personal representative of the High Priest. JoAnn Watson points out “The servants of the high priest were known to perform the underhanded dealings of the high priest” (“Malchus (Person),” ABD 4:487).
It is likely that this is a badly aimed attack rather than an attempt to maim the man so he was no longer permitted to enter the Temple. Maiming priests by cutting off their ears is well known in the Second Temple Period. Rather than a blundering attempt to save Jesus, this may have been a calculated attack on the man in charge of the arrest. Rather than killing him, Peter humiliated him and rendered him useless as a servant of the High Priest.
Peter’s actions are sometimes dismissed as laughable, but they represent the actions of the most zealous of Jesus’ followers. Jesus wanted to protect them by giving himself up to the arresting guards, but Peter seizes the moment and “starts the revolution.” Even if this is a colossal failure, it is better than the response of the rest of the disciples! Jesus orders Peter to put his sword away, telling everyone that he intends to “drink the cup the Father has given him,” is a reference to the cup of God’s wrath, the crucifixion which he is about to face.
Peter is therefore not a bumbler who can’t do anything right, but the most faithful of Jesus’ disciples and seems willing to attack an important and potentially powerful member of the High Priest’s household.