Answer:
Trudged - walked slowly due to tiredness or the harsh conditions encountered. When someone is feeling exhausted and tired due to the conditions he has passed, his slow steps and pace in walking suggests he is trudging.
The context clue here is seen in to march into the darkness.
Explanation:
The context clue helped to give me the clue to the meaning of trudged. Since they ...to march into the darkness, this reveals the condition that made them to trudge along silently behind them.
