“During the great invasions, the German people who were migrating in the Roman Empire had a certain number of words depending on the root mark. It is from a name marka, meaning "sign indicating a limit", "limit, frontier", that is coming the French word "marche", describing a frontier zone…”
Marchal being a typically Lorraine (north-east of France) name (the French "from the inside" never succeed to spell it correctly) therefore means "frontier man". And these are those frontiers that flirt with infinite that I invite you to discover.