George Adam Martin wrote the following account:
It happened that Count Zinzendorf and many of his brethren came into the country and occasioned a great stir, especially by his synods. And because all denomonations were invited to them, I too was delegated by my superintendent (Martin Urner) to attend them. When I arrived at the synod which was held at Oley, I found there some of our Brethren.... The count himself was president and for three days I heard queer and wonderful things there. After my return home I went to my superintendent and said that I looked upon the count's conferences as snares, for the purpose of bringing simple-minded and inexperienced converts back to infant baptism and churchgoing and of erecting the old Babel again. We consulted with each other what to do, and agreed to get ahead of the danger, as some Brethren had already been smitten with this vain doctrine, and to hold a yearly conference, or, as we called it, a great meeting, and fixed at once the time and place. This is the beginning and foundation of the great meetings of the Brethren.
Source: A Self-Instruction Guide Through Brethren History, Donald E. Miller