Learn French: Fatigués par le voyage, nous avons grimpé sur la grande dune. - Exhausted by the trip, we climbed the large dune.

Even though fatigués sits by itself at the beginning of the sentence in a detached phrase, it still functions as an adjective describing the main subject, nous. Because nous is a plural pronoun, fatigués must agree with it by taking a plural -s.

Does the detached phrase fatigués par le voyage just describe the speakers, or does it do something more?

In French, starting a sentence with a detached adjective or past participle usually implies a logical connection to the main action. While this often expresses a cause (e.g., 'because we were...'), here it creates an implied contrast or concession: 'Even though we were exhausted by the trip, we climbed the dune.' It is an elegant way to connect ideas without using conjunctions like bien que.

Since grimper (to climb) involves physical movement, why does it use avoir instead of être in the passé composé?

While many common verbs of change of location or movement (like aller, monter, or descendre) use être, grimper is an exception and takes avoir. You only use être with a specific, closed list of verbs (often memorized as Dr. & Mrs. Vandertramp), and grimper simply is not on that list.

Why is the adjective placed before the noun instead of after it?