thick at their foundation and with a height of 6 meters. It was enclosed by a 15-meter wide and 5-meter tall ditch. The circuit of the walls was 700 meters long and the fort encompassed an area of 4 hectares, not including a possible outer fort. Filling in a 200-meter section of the ditch was necessary for Henry's men to storm the walls, a process that would have required the excavation of 15,000 tons of earth with at least 50,000 man-hours of work. The earth then needed to be transported and unloaded on the ditch using wagons. At least 750 carts and 30,000 wagon-loads of earth would have been needed, requiring another 60,000 man-hours of loading, transport and unloading. With only 8 hours of daylight in the winter, it would have taken 1,000 men two weeks to accomplish the task. Once Gana was stormed at the end of the 20-day siege, Henry gave the order for his men to kill all the defenders and enslave the young boys and girls to his milites professional soldiers. Given the ferocity of the German conquest, it is likely they had sustained heavy losses in the assault. Bachrach estimates more than 1,000 Germans killed or wounded, based on a mathematical siege attack model for the Brandenburg fortification. Aftermath After conquering Gana, Henry marched up the Elbe to accomplish his ultimate campaign aim, the siege of Prague and the subjugation of Duke Wenceslaus I's Duchy of Bohemia. Along the way, he constructed a fortress at Meissen, as proven by dendrochronological dating of the wooden construction at Meissen, which establishes an early building stage for 929. Meissen secured German control over the middle Elbe and was followed by the establishment of the Marca Geronis to maintain the German hold. With the help of Duke Arnulf of Bavaria's troops, Henry invaded Bohemia with a total force of 12,000–15,000 professional soldiers and expeditionary militia levies and compelled the surrender of heavily-fortified Prague, concluding a highly successful campaign. Analysis The extensive and successful German siege operations over some period of time show that Henry and the German kingdom could mobilize thousands of soldiers and supply them with the transport animals, food and fodder necessary to maintain them. Citations Bibliography 929 Gana Gana Gana