Final answer:
The Han Dynasty's significant military problem was managing conflicts and maintaining borders against the northern Xiongnu confederation, requiring strategic adaptations including peace treaties, restructuring their military with professional soldiers, and enduring internal political challenges.
Step-by-step explanation:
Significant Military Problems Faced by the Han Dynasty
The Han Dynasty faced significant military problems, primarily with the northern Xiongnu confederation. Early attempts by the Han to establish autonomous regions, like the fief of Hann, led to conflicts and defections to the Xiongnu, triggering wars that the Han initially could not win. Han's founder, Liu Bang, tried to contain the situation by sending large forces to suppress rebellious kingdoms and attack the Xiongnu but suffered defeat, which led to a marriage alliance and tribute system to maintain peace.
The Han had to restructure their military, shifting from a universal male draft to hiring professional soldiers, to effectively combat the Xiongnu cavalry. Additionally, they faced internal and external political challenges, as well as uprisings and incursions from various tribes and confederacies. The shifting political and military landscape required the Han to make adjustments, including the assimilation of conquered or allied tribes and the placement of military colonies to defend its borders.
Throughout its existence, the Han Dynasty's military capabilities and governmental structure were significantly affected by the threats posed by the Xiongnu and other non-Chinese tribes, influencing the empire's strategic and military adaptations.