Breakdown of Falls wir wandern gehen, musst du den Reiseführer mitnehmen.
du
you (informal singular)
wir
we
gehen
to go
müssen
to have to, must
Questions & Answers about Falls wir wandern gehen, musst du den Reiseführer mitnehmen.
Why does this sentence use Falls instead of Wenn?
While both can be translated as "if", falls translates more specifically to "in case" or "in the event that." It is used to express a condition where there is a bit more doubt or uncertainty about whether it will actually happen. Wenn is a more neutral "if."
Why does the second half of the sentence start with the verb musst instead of du?
The entire subordinate clause (Falls wir wandern gehen) occupies position one of the overall sentence. Because German requires the conjugated verb of the main clause to be in position two, musst must come immediately after the comma, which pushes the subject du to position three.
In the first clause, why is the word order wandern gehen instead of gehen wandern?
In a subordinate clause (triggered here by Falls), the conjugated verb must go to the very end of that clause. Here, gehen is the verb being conjugated to match wir, so it takes the final spot right after the infinitive wandern.
Since mitnehmen is a separable verb, why isn't the prefix mit- separated here?
The presence of the modal verb musst means the main action verb must be pushed to the end of the clause in its full infinitive form. Since mitnehmen is not being conjugated here, its prefix stays firmly attached.