What exactly is a memorial anyway?
Webster's says "something that keeps remembrance alive."
As the children of Israel entered the Promised Land, they were instructed to build a memorial to remember the God who had led them there. It was to serve as a discussion topic for their children, a means of passing down a reverence for God.
In a similar way, on Memorial Day we are to remember the God who has greatly blessed us and those who have served our country. On Memorial Day, we do well to remind our children and those who follow after us what the cost of our freedom is.