Complex sentence: Maarten van Rossum (Zaltbommel, c.1490--Antwerpen, June 7 1555) was a Dutch Guelderian military tactician and later field marshal at the service of Charles of Guelders.
Split into simpler sentences: Maarten van Rossum (Zaltbommel, c.1490--Antwerpen, June 7 1555). Was a Dutch, Guelderian to be exact, military tactician and later field marshal at the service of Charles of Guelders.