Sentence:  By fall , 443 survivors of this <WSD>arduous</WSD> journey were clustered about Fort Snelling , but most of them were sent on to Galena and St. Louis , with a few going as far as Vevay , Indiana , a notable Swiss center in the United States . 
Meaning of the word marked with <WSD> tags:  characterized by effort to the point of exhaustion; especially physical effort