Just as the effect of Confirmation, which is spiritual strength, presupposes the effect of Baptism, which is justification, so the sacrament of Confirmation presupposes the sacrament of Baptism. [ad 3]
Here we see again that we receive justification through Baptism – that God justifies us through Baptism.
Secondly, Aquinas agrees (centuries beforehand!) with the Catechism that although "God has bound salvation to the sacrament of Baptism, … he himself is not bound by his sacraments" (CCC §1257):
The Divine power is not confined to the sacraments. Hence man can receive spiritual strength to confess the Faith of Christ publicly, without receiving the sacrament of Confirmation: just as he can also receive remission of sins without Baptism. [ad 1]
This is one part of the reason why, although "the Church does not know of any means other than Baptism that assures entry into eternal beatitude," (CCC, op.cit), the Church teaches that salvation is indeed possible for those who have never heard of Christ or the Church.