The following year, he was released from detached service and assigned to Company K, 26th Regiment, 1st Infantry Division when it arrived in England.

He served with his division throughout World War II in an infantry rifle company, being promoted through the ranks to first sergeant.

After attending the 1st 3 Graders Course, Oahu Officer Troop and Staff School, at Schofield Barracks, Hawaii, he was assigned to Headquarters, Eighth United States Army, South Korea as a member of the occupation forces.

Wooldridge and General Harold K. Johnson, the Chief of Staff of the United States Army, worked together as an effective professional team.

He is the only Sergeant Major of the Army to return to field duty after serving in the top enlisted position.

In 1969, while command sergeant major of MACV, Wooldridge was accused in a congressional inquiry of fraud and corruption related to the military club system, amounting to more than $150 million annually.

[3]: 46–7  Turner was later accused of having covered up an attempt by Wooldridge to smuggle 8-9 cases of liquor aboard General Creighton Abrams' KC-135 jet in April 1967.

[3]: 55  The subcommittee concluded that Turner had given Wooldridge and his associates immunity from investigation and "was grossly negligent in the performance of his official duties.

[4]: 210  Higdon testified that between then and July 1968 Crum paid him a total of approximately US$60,000 of kickbacks from the slot machine operations.

[4]: 76  In August 1968 Wooldridge brokered a deal between Crum and Maredem Inc. (a company owned by Wooldridge, Higdon and Sergeant Hatcher, the custodian of the 1st Infantry Division NCO clubs) under which Maredem would have the monopoly on snack items in the NCO clubs while Crum would have the monopoly on slot machines.

In June Collins and Robin Moore's novel Khaki Mafia, a fictional character in a criminal cartel is based on Wooldridge in South Vietnam.