Article one's account of Chalcedon in 451 settles how many natures Christ has. It does not settle how many wills or modes of operation he has, and that further question produced its own council, its own condemned position, and its own martyr.
Seventh-century theologians proposed monoenergism, that Christ acts through a single divine-human energy, and then monothelitism, that he has a single will, as compromise formulas intended to win back the Oriental Orthodox churches article one describes without reopening Chalcedon's two-natures settlement itself. Maximus the Confessor argued that a nature without its own will and operation is not a complete nature at all, so that a single will in Christ would mean he did not possess a complete human nature, quietly undoing Chalcedon's own achievement under cover of appearing to defend it. For that position Maximus was tried, had his tongue cut out and his right hand amputated by imperial order in 662, specifically to stop him from preaching or writing further, and died shortly afterward in exile.
The Third Council of Constantinople, meeting in 680 and 681, vindicated Maximus's position after his death, condemning monothelitism and monoenergism and confessing two natural wills and two natural operations in Christ, undivided, unconfused and unopposed to one another, corresponding exactly to the two natures Chalcedon had already defined. The council's formula follows Chalcedon's own logic to a conclusion Chalcedon itself had not made explicit, and it is a clear instance of a settled dogma generating a further, genuinely new dispute rather than closing the subject, decided in the end by a council condemning what an emperor had spent decades trying to impose as a unifying compromise.