Even though he "died for orthodoxy and obedience to Rome" and "is commemorated in the Roman Martyrology on 13 August," (source) St Maximus is not familiar to many Western Christians. No doubt, this has to do with the fact that he was a defender of the Fifth Ecumenical Council and the prime theologian whose writings undergirded the Sixth Ecumenical Council. These two councils dealt with Christological controversies that arose after the famous Fourth Ecumenical Council of Chalcedon. These controversies--the monophysite and monothelite (as well as monenergism)--arose chiefly in eastern lands and so did not directly touch the western churches. In fact, it is not unfair to say that the western churches have effectively ignored, or at least grossly under-studied, the controversies leading to and decisions resulting from the Fifth & Sixth Ecumenical Councils. (Here is a brief overview.)
In the last half-century, however, interest in the writings of St Maximos the Confessor has picked up among western Christians. Two Roman Catholic theologians whose scholarship gave rise to this study were Dom Polycarp Sherwood and Hans Urs von Balthasar (who thoughts have profoundly influenced Pope Benedict XVI).
St Maximos the Confessor was a righteous man, courageously speaking against bishops and patriarchs who harbored schismatics or heretics, or who themselves sided against the Council of Chalcedon. When he was seventy, St Maximos assisted Pope Martin during the Lateran Council (649 AD; a local council) which the pope had convened to condemn the patriarch of Constantinople of monothelitism. (Monothelitism teaches that Christ had only one [divine] will, thereby denying his full humanity.) Pope Saint Martin I was later dragged from Rome and died in exile as the last martyred pope.
Concerning Rome, St Maximos wrote:
The extremities of the earth, and all in every part of it who purely and rightly confess the Lord look directly towards the most holy Roman Church and its confession and faith, as it were to a sun of unfailing light, awaiting from it the bright radiance of the sacred dogmas of our Fathers according to what the six inspired and holy councils have purely and piously decreed, declaring most expressly the symbol of faith. For from the coming down of the incarnate Word amongst us, all the Churches in every part of the world have held that greatest Church alone as their base and foundation, seeing that according to the promise of Christ our Saviour, the gates of hell do never prevail against it, that it has the keys of a right confession and faith in Him, that it opens the true and only religion to such as approach with piety, and shuts up and locks every heretical mouth that speaks injustice against the Most High. (source)Like the Roman pope, St Maximos also suffered a martyr's death. Because of his efforts at the Lateran Council, St Maximos was arrested and tried several times and exiled. Finally, 13 years after the conclusion of the Lateran Council, because he was aligned with Pope St Martin I and would not recant, St Maximos was put on trial in Constantinople. During the trial, Pope St Martin I was posthumously anathematized and St Maximos was sentenced to exile. But before being exile, the right hand and tongue of this 82 year-old man were amputated so that he could not longer write or preach. He died shortly after he arrived in exile. (Sherwood, 27-28)