Was grace given in the baptism of John?

The Council of Trent (Session VII, canon 1 on baptism) anathematized the teaching that John's baptism had the same effect as Christ's.

St. Thomas Aquinas explains in the Summa Theologica that all John's teaching and work prepared for Christ, as an under-craftsman prepares material for the master craftsman. Grace was to come through Christ, for "grace and truth came through Jesus Christ" (John 1:17). So John's baptism did not confer grace but prepared the way for it in three ways:

1. by John's teaching, which led people to faith in Christ;
2. by accustoming people to the rite of Christ's baptism;
3. by penance, preparing them to receive the effect of Christ's baptism.