Henry I and Otto I were two of the most successful medieval Kings of Germany, and between then founded an Imperial dynasty, often taken as the start of the Holy Roman Empire. Henry I became king of East Francia, the second non-Carolingian holder of that title (and the first successful one, after Conrad I struggled to maintain his power). Otto I was his second son, and the first member of the family to be crowned Emperor, after a lapse of some forty years with no holder of that title. Over the course of 54 years the two men established their dynasty as a major power across Europe, campaigning from the Oder to the Seine, and deep into Italy. Much of their success was due to their military achievements, and their ability to bounce back from serious setbacks - Otto needed several campaigns to establish his power in Italy, and faced a series of dangerous civil wars, Henry had to deal with major Hungarian invasions.
This book examines the nature of warfare during their reigns, looking at a wide range of topics, from basic training to the actual campaigns. The main argument is that warfare during this period was both more professional and on a larger scale than is generally acknowledged. This argument is supported by an equally wide range of sources, and indeed one of the arguments is based on the large number of copies of military textbooks known to have existed in Germany in this period. This evidence for the availability of a military education is backed up by the chronicles, which often describe particular noblemen as being skilled military leaders, showing that this was seen as a useful skill (although also suggesting that it wasn't entirely common).
I'm not entirely convinced by the details of the author's arguments about the size of Ottonian armies, which is based to a large extent on a series of sieges. The size of the garrisons are estimated based on the size of the walls and known figures for the ideal number of defenders, and the size of the attacking army is based on a multiple of that figure. Mainz had a 3,850m long wall, which would have required 5,000 men to satisfy the near contemporary Anglo-Saxon requirements of one man for every 1.3m. Based on the idea that an attacking army needed to be four or five times bigger than the garrison to be able to storm a city, an attacking army of 25,000-30,000 is calculated. There are two problems here. The first is that we don’t actually know how big the garrison was, and the second is that Otto's attacks on the city failed. A smaller attacking army could have been held off by a smaller garrison, and with no firm figures for either, we don’t know if 25,000 men attacked 5,000 men, or 10,000 men attacked 2,000 (or any variant on the theme). Having said that, the scale of warfare conducted by Henry and Otto suggested that they did have access to fairly sizable armies, as does the amount of fortifications known to have garrisoned at any one time.
This is a fascinating study of a period I'm not terribly familiar with, backed up by a good use of the original sources, and painting a picture of two successful rulers of a powerful and well organised kingdom.
1 - Restoring Francia Orientalis: Henry I's Long Term Strategy
2 - Forging a New Empire
3 - Military Organization
4 - Military Education
5 - Arms and Training
6 - Morale
7 - Tactics on the Battlefield
8 - Campaign Strategy: The Civil War of 953-954
Appendix: Major Military Operations by Henry I, Otto I and Their Commanders
Author: David S. Bachrach