This paper explores the Church of England's recent views in the area of war and defence, drawing attention to its just war thinking recently revived by several theologians and churchmen. As a national established church, the Church of England has developed its own approach to modern warfare to meet the political circumstances of the day, on the one hand, and to place strong moral limits on the use of force, on the other. The paper attempts to review several uses of just war theory within Anglicanism in the contexts of the Second World War, nuclear deterrence in the Cold War, humanitarian intervention, the 'war on terrorism' and the Iraq War. On Iraq's case, the paper reflects on arguments by Dr Rowan Williams, the current Archbishop of Canterbury, and Richard Harries, the former Bishop of Oxford and the Church's leading expert on just war theory, who both criticised the war in Iraq as unjust. Through this, I ask how the Church's changing attitude towards warfare highlights another unsettled question, namely the relationship between church and state in Britain, and, given the Church's moral concern, whether it benefits from being an Established church.