This paper provides the most comprehensive and extensive analysis to date of the possibility of a ''rally 'round the flag'' effectFan increase in support for the government caused by involvement in international conflictFin Britain, for the years 1948-2001. We use a fractionally integrated time series model with an array of political and economic controls. Our primary dependent variable is intention to vote for the ruling party. The results confirm earlier studies that the Falklands War generated a rally effect, but they provide a more sophisticated understanding of the Gulf War rally. New results also include the findings that participation in international crises which stopped short of war did not engender rallies, and that there were no rallies for the Korean, Suez, or Kosovo Wars. The findings indicate that when they do occur rallies are heterogeneous in nature, that rallies are most likely when there is intense and direct threat to the national interest, that the relationship between multilateralism and rallies in the British case is tenuous, and that rallies for the ruling party are sometimes expressed through satisfaction with the prime minister.Does involvement in international conflict affect a democratically elected government's popularity? Much of the empirical work on the so-called ''rally 'round the flag effect'' has to date been limited to exploration of the American case. In this paper, we test for the presence of rally effects in the United Kingdom. Past research has found that the Falklands War boosted Prime Minister (PM) Margaret Thatcher's popularity in the early 1980s, helping carry her to victory in the 1983 election. However, there are virtually no comprehensive studies exploring whether British conflict involvement has affected government popularity across a long time span, searching for the general effects of conflict on the popularity of British governments.This study aims to fill that gap. We ask the question: In the post-World War II period, has the popularity of the British government significantly increased when