TOUR OF DUTY

In the military, a 'tour of duty' is a period of time spent at sea or assigned to service in a foreign country.
For example, in World War II a tour of duty for a RAF (Royal Air Force) bomber crew was 30 flights. That number could take up to 12 months.
A general tour of duty comprises service that can last from one to four years. Generally duties that last longer than 2 years are eligible to receive medals of merit related to their service. Tours of duty can also be extended involuntarily for service members, such as in September of 2006 when the tour of duty was extended for 4,000 military personnel in Iraq.