Final answer:
The 1529 meeting between Martin Luther and Ulrich Zwingli that highlighted their disagreement on the nature of the Eucharist was the Colloquy of Marburg.
Step-by-step explanation:
The famous 1529 meeting between Martin Luther and Ulrich Zwingli at which they could not agree on the presence of Christ in the communion bread and wine was known as the Colloquy of Marburg. Luther and Zwingli's disagreement on this critical point of Eucharistic presence prevented the unification of their Protestant movements. While Zwingli viewed the Eucharist as symbolic, Luther held on to the belief in the real presence of Christ in the sacrament, albeit without accepting the Catholic doctrine of transubstantiation.