Adler, who entertained U.S. troops in Africa, the Middle East and the South Pacific during World War II, insisted on a non-segregation policy between white and black audience members.
He fled to Britain in the 1950s after being targeted as a communist during the McCarthy witchhunt.
The famed musician worked to aid Israelis during the 1967 Six-Day War and 1973 Yom Kippur War.