Final answer:
Crossing difficult terrains like salt-marshes, swollen rivers, or hilly areas requires specific strategies for safe and efficient traversal. It's important to act quickly in marshes, wait for rivers to subside, and use the natural topography to one's advantage on hills. Precautions like routing step on bridges to prevent forced oscillations highlight the required vigilance in such situations.
Step-by-step explanation:
To cross over an obstacle or bumps such as salt-marshes, rivers after heavy rains, or hilly terrain, differing strategies are advised.
When crossing salt-marshes, the focus should be on quick traversal. If a confrontation is necessary within such an area, it's crucial to have water and grass nearby and to place oneself against a backdrop of trees for defensive advantage.
When encountering a swollen river, the advisable course of action is to wait until it subsides. In general difficult terrain, setting up camp is discouraged and it's recommended to unite with allies at intersecting high roads instead.
It is essential to remain vigilant and cautious.
For instance, when on a hill or a bank, it's beneficial for both the comfort of the soldiers and the tactical advantage to occupy the sunny side with a downward slope on one's right rear.
A similar instance of precaution is when soldiers are ordered to route step across a bridge.
This tactic, namely 'route stepping', prevents the synchronicity of footsteps from creating resonant frequencies that might cause the bridge to oscillate dangerously.