Tet is the Vietnamese New Year. In early 1968, the U.S. leadership in Vietnam determined that the U.S. troops could relax over the Tet holiday because the PLAF (South Vietnamese Communist Army) would be celebrating. However, on January 30, the PLAF began what is now known as the Tet offensive, where 22 major U.S. installations were attacked. The U.S. beat back all of the Tet offensive attacks. The real battle that the PLAF won was in the minds of the American people. Tet turned the tide of U.S. public opinion against involvement in Vietnam.