I had always been confused by this event, because the Jews celebrated Sukkot and some Christians make it the Day of prayer for the peace of Jerusalem around this time. I was made aware of it in 2008 when my church and the American English service (2nd Presbyterian Church) have this annual combined service, pulling our usual service an hour earlier.
World Communion Sunday, celebrated on the first Sunday of October. Originated at Shadyside Presbyterian Church, Pittsburgh, by The Rev. Dr. Hugh Thomson Kerr, in 1933, to seek union among churches, during the great depression. Source: Wikipedia.
Rev. Kerr also wrote a hymn "God of our life, through all the circling years" in 1916, for the church's 50th anniversary.
I supposed should I visit Pittsburgh, this church must be on my list of visit.
Some of Kerr's books may interest me: A God Centered Faith, The Christian Sacraments (a classic reference) and Preaching in the Early Church.