Perhaps the most important question to be examined in a review of Australian defence policy during 1971–75 is how much fundamental change occurred. There is a strong prima facie case for holding that the period was the most consequential five years for Australian defence policy since the Second World War. The change of governing parties in late 1972 marked the end of an era when foreign and defence policy issues played a significant part in determining the outcome of the seven successive general elections won by the Liberal and Country Parties between 1951 and 1966. Even in 1969, Australian involvement in Vietnam was not sufficiently unpopular to unseat the Gorton Government which was troubled on many fronts. Because defence was an important electoral issue throughout the 23 years of Liberal-Country Party rule, it seemed only reasonable to expect marked changes in this area following their loss of office.