When Do Ideologies Produce Alliances?. The Holy Roman Empire, 1517-1555

Recent research suggests a conditional relationship between states' domestic regimes or ideologies and their alliances. I argue that the likelihood that alliances will form along ideological lines increases with the fear among at least two governments of ideology I that they are threatened by transnational rival ideology J. Understanding the power of demonstration effectsFthat when J advances in one country it gains credibility in othersFI-governments will have an incentive to enter an international agreement to oppose J domestically. Such domestic-security agreements will exacerbate the security dilemma, raising fears among J-governments that I-governments are forming a bloc directed at J and J-governments. J-governments will tend to respond by increasing cooperation among themselves, inducing corresponding fears among I-governments; the coalescing I-and J-blocs will tend to spiral into alliances. I-or J-governments wishing to avoid ideologically based alliances may signal an absence of rollback intentions through various means. I demonstrate this process of alliance formation with a lengthy case study of alliance formation in the Holy Roman Empire in the sixteenth century.