The Troubles at Frankfurt was a name given retrospectively to internal quarrels of the Marian exiles in Frankfurt am Main in the mid-1550s, involving also the Scottish reformer John Knox. Politically, Frankfurt was a Free imperial city of the Holy Roman Empire.
In the summer of 1554, the English exile community in Frankfurt was sharing a church with the congregation of Valérand Poullain, and was led by the expatriate William Whittingham. They adopted liturgical practices, under some pressure from the local magistrates, that differed from what was laid down in the Second Prayer Book of Edward VI, of 1552. When Whittingham sent a declaration of unity to other exile groups, in August, Strasburg prepared to send one of more its leaders, to take matters in hand. The Frankfurt group responded by making known its intention to elect three ministers. T
According to A Brief Discourse, the major source for these events, John Knox was sent as a minister to Frankfurt from Geneva by John Calvin. He led the opposition to the "prayerbook faction", the supporters of the 1552 Prayer Book. Edmund Grindal came with a group from Strasburg, and had dealings with Knox. Grindal then wrote about the situation to Nicholas Ridley in England; who found the local compromise, in line with what happened for other exile groups, quite reasonable, but had some criticism of Knox's approach. Knox and Whittingham at this point pushed for a definition of essentials in the Prayer Book, causing Grindal to depart rather than be seen to negotiate.
The initial conflict centered on the order of the communion service. Knox would not use the Genevan order since it would offend others, but neither would he allow the use of the English prayerbook form. Thomas Lever led an attempt to construct a compromise order. The prayerbook faction was led by Richard Cox, who had left Strasburg to correct the situation in Frankfurt. However, others in Strasbourg and some who had moved from there to Frankfurt, opposed the prayerbook, so both congregations were divided from within. Some people may have remained out of the fight, and others, like Lever, changed sides over time. (In Knox's own account, Lever—who was his co-preacher—failed to support him and thereby exacerbated the division.)