When the Warsaw Pact invaded Czechoslovakia in 1968, Hammer's studies at the Academy were cut short, and he moved to the United States and resolved to become a citizen after receiving a scholarship at Berklee College of Music in Boston.
Hammer's studies at the Academy were cut short. The Warsaw Pact invaded Czechoslovakia in 1968. He moved to the United States. He resolved to become a citizen after receiving a scholarship at Berklee College of Music in Boston. The Warsaw Pact invaded Czechoslovakia in 1968.