What does this sentence mean exactly?

Question

I've started playing a visual novel and came across this sentence in the first minute of, in lack of a better term, gameplay.

学校【がっこう】の軍隊【ぐんたい】が出陣【しゅつじん】してもう二週間【にしゅうかん】たったけれど、全然【ぜんぜん】戻ってくる【もどってくる】気配【けはい】ない。大丈夫【だいじょうぶ】なのかな。

I know that this roughly translates to:

Although the school's armed forces left 2 weeks ago, there's still no sign of them returning. I wonder if they're alright.

The problem I have is with the tense. My teacher taught me that Japanese tense is realised by the last verb in the sentence. So why does たつ take たった here?

Answer 1

Aha! It sounds like you've been told that verbs in Japanese are conjugated only at the end of a sentence--e.g., if you want to put a verb in the middle of a sentence, it should be in て form, and then the tense of the sentence is determined by the conjugation of the final verb.

This isn't true. It's sort of true for clauses, however, and this sentence has two clauses separated by a disjunctive (けれど). As in English, it's totally fine and common in Japanese to take two separate thoughts which could exist as standalone sentences and combine them into one sentence with "but." For example:

東京に行った。寿司は食べなかった。

I went to Tokyo. I didn't eat Sushi.

東京に行ったけど、寿司は食べなかった。

What's different in Japanese is that it's less common than in English to combine clauses with an explicit nondisjunctive conjunction, hence the common beginner mistake of using と to combine clauses. That's when you use て form:

公園に行って、犬を見た。

I went to the park and saw a dog.

公園に行ったけど、犬を見なかった。

I went to the park but didn't see a dog.

Is this what you were asking?