The story of the song's genesis is here.
At our church, yesterday, the one mention of Memorial Day was by Sue, the person leading the Prayers of the People, which we always have in both formal and informal form: in the second half, anyone can offer a prayer, and many people do. Sue prayed (I am paraphrasing): "Let us pray for all the brave men and women who have died in service to our country [she may have said "their country" or "their countries," I can't remember -- I know she wasn't just remembering U.S. dead, she is active in various efforts for peace, including the situation in Sudan], and let us pray that soon, very soon, no more people will join their number."
For those of you who have Peter, Paul, and Mary nostalgia, here's their version...
Joan Baez is still singing the song today. This (YouTube in post below) will bring back memories for some of you, and speak to this Memorial Day for many. Joan Baez sang this with mothers who had lost children in war, and then again at the concert recorded on the YouTube below.