Breakdown of Mesmo exausto, ele rastejou pelo pântano.
ele
he
por
through / by / for / because of
o
him/it (m)
mesmo
even (mesmo eu = even I)
Questions & Answers about Mesmo exausto, ele rastejou pelo pântano.
Why is there no verb in the first part of the sentence? Don't we usually say mesmo que ele estivesse?
You can absolutely say mesmo que ele estivesse exausto, which uses the subjunctive. However, this sentence uses a verbless concessive structure. Because the subject (he) is the same for both parts of the sentence, you can drop the verb and the word que, placing Mesmo directly before the adjective. It means "Even exhausted" and is a very natural, concise shortcut in Portuguese.
Does the adjective exausto change if the subject changes in this verbless structure?
Could I mix the two structures and say Mesmo que exausto?
No, that would be grammatically incorrect. The rule is strict: if you use que, you must include a conjugated verb in the subjunctive, as in mesmo que ele estivesse exausto. If you want the short, verbless version, you must drop the que entirely and just use Mesmo.
Why use pelo instead of através do for "through" the swamp?