That's right Bill. A special group during the fight for Rotterdam. To be more specific; These are the Rotterdam Marines Corps. Battle for the Maas Bridges. There is a lot of information on the Internet about this Heroic Marines corps.
Some Photos I found on a quick survey. Mobilization Typical Dutch uniform and Helmet, 2 soldiers of Corps Mariniers Rotterdam, Zwarte Duivels View on one of the Maas Bridges, nowadays we call this one "De Oude Hef" Surrender
5 days of heavy fights, defending the Bridges and the city of Rotterdam.