The Mark on the Rhine

**January 911. The oath a Danish chieftain swore at his own hall six winters earlier comes due. A trader at Hedeby sends a second report to Metz: the keels are being laid. A duke of Lotharingia who has spent ten years building a system for the eastern steppe has eighteen months to build a second front on a river-system the system was never designed for.**

Across the two calendar years the book covers, the realm meets a frontier it has never fought on. Ota goes to Nonnberg to die; Hedwig comes back from Vienne and stays; a boy of four at the opening learns to read small Latin by the close. On the Rhine a boom-and-chain works is laid at Duisburg; a Frisian rowing cohort is raised at Dokkum; and, in the high summer of 912, sixty Norse keels under Gorm's son Thorkel come up the river on the feast of Saint John and are met by a running fight that ends at the boom in a night battle the realm will afterwards call by the name of the town.

The Mark on the Rhine is the sixth volume of Rise of the Franks. It is the book about the year in which a reform built for one frontier was bent, at serious cost, to a second — and the year at the end of which a duke of twenty-seven was told, by a letter the chancellor read twice before he handed it over, that the man who would succeed Louis the Child would need Lotharingia to choose.