The number of American military personnel in Vietnam increased dramatically, from 16,000 advisors in non-combat roles in 1963 to 525,000 in 1967, many in combat roles. (Convention chairman LeRoy Collins' declaration of a two-thirds majority in favor by voice vote is even disputed. )Seymour Hersh stated that Robert F. Kennedy (known as Bobby) hated Johnson for his personal attacks on the Kennedy family, and later maintained that his brother offered the position to Johnson merely as a courtesy, expecting him to decline.