(Did you mean a Melbourne, British or New York convention?)

from Fancyclopedia 2 ca. 1959
(DAG) or All-Fools' Con (Latter name from the date). A small but select conclave held at Fond du Lac, Wisc, on Easter Sunday 1 April 1956. Attending were Dean and Jean Grennell (their home), Redd Boggs, Curt Janke, and Dick Eney. It coincided with the date of the British convocation at Torquay that year, and the name "Eastercon" was in honor of the Westercon. A one-shot was produced and the Nuclear Fizz established in Wisconsin.
Wikipedia Fanac File770 Ansible
Concatenation Fanlore Files https://duckduckgo.com/?t=lm&ia=web&q={$name} (IA) Website 1956 . .