Fortissimi and Validissimi, the strongest and bravest, was how Roman writers described the Batavians. Natives of the Lower Rhine, they were a community of soldiers who supplied the Roman army with men. Led by their native aristocracy, loyal and fierce, they became elite soldiers, personal bodyguards to the emperors and the empire's most valued European auxiliaries.

The book draws on many sources, Roman historical writings, Latin inscriptions and archaeological finds. The author is a coordinator of the excavations at the site of a camp of a Batavian cavalry troop. The history of the Batavians in Roman service includes remarkable events: a rebellion against Rome on the Lower Rhine, a bloody battle with the Caledonians in Britannia, a cavalryman crossing the Danube in full armour in front of the Emperor Hadrian, and a troop commander being called 'rex' while being asked for more beer for his men.

Fortissimi and Validissimi is a compelling history for academic historians, enthusiasts of history and re-enactment communities.