At each stop, there were prayers and talks and songs, all invoking the name of God. In the above photo, the man in black in front of the colors is a clergyman reciting his prayer at the Navy memorial. Songs included God Bless America and America the Beautiful "God shed His grace on thee". An orator spoke Lincoln's Gettysburg Address, using the version that includes "this nation, under God."
As I enjoyed the moving spectacle, I thought about John's Topic on Constitutional Change, allowing local jurisdictions to establish an official religion within their borders. John, IMHO, is rightly concerned that that the First Amendment phrase "Congress shall make no law respecting an establishment of religion ..." has been misused to prevent public display of religious symbols and speech. However, I remain convinced that the remainder of that text, "...or prohibiting the free exercise thereof" is sufficient to protect our right to use public property for the free exercise of our religious beliefs.
Massachusetts is the bastion of left-wing government, yet, even here, people are still free to express their religious beliefs in a publicly-sanctioned event. I am sure Chatham is not the only town to do so. Indeed, any town that does not have a similar celebration would be the exception.
PS: Vi and I are in Chatham for a week along with some members of my NY bicycle club. Nine of us rent a cottage in this picturesque town every year and we enjoy bicycling, kayaking, eating - and a traditional Memorial Day celebration.