The increasingly fragile unity of the order was placed under a heavy strain in the 1290s when the first fissures appeared with the withdrawal of friars who placed themselves under the protection of Pope Celestine V. Two of the most influential spokesmen for the reformers were Ubertino da Casale and Angelo Clareno.

Ubertino da Casale (1259 – c. 1330)

Ubertino da Casale, who enjoyed contact with Angela of Foligno and Margaret of Cortona, was the leader of the reformers in Tuscany and Umbria. He had served as lector at Santa Croce in Florence alongside Peter Olivi for two years. His nine years in Paris gave him an international outlook on the order and its practices; this global perspective countermanded his critics' claim that he was unfamiliar with life in the vast majority of provinces. His Arbor vitae crucifixae Jesus and his Super tribus sceleribus reflect the deepening tensions within the order regarding the observance of the Rule.

Ubertino's Rotulus, delivered in a polemical context at Avignon, laid out the case for far-reaching reforms under twenty-five headings and influenced aspects of Pope Clement V's Exivi de paradiso of 6 May 1312, the last signi- ficant papal attempt at a compromise between the two wings of the order. A historical model permitted Ubertino to contrast the halcyon days of the founder with the decline of contemporary friars.