I recently learned that the town of Gloucester, MA has compiled a list of fishermen lost at sea and other drownings. The full PDF list is located here and goes back to at least the late 1700s. As a note, some of the deaths listed are quite sad, so if you're not feeling up to reading about drownings then don't look at that document. It's a very interesting document, but definitely sad.
I was looking through that list and found the entry for William Elwell, who died between 1812 and 1815 (search the document for "Elwell, William" if you want to find the specific entry). He's listed as being on a trading vessel/journey and the circumstances of his death are listed as:
went to Lisbon in time of the long embargo and was never heard of again after leaving port for home
What was this long embargo and why would a man from Gloucester have gone to Lisbon because of it?
It's almost certainly referring either to the Embargo Act of 1807 or one of its successor bills. This made it illegal for vessels under American jurisdiction to ship goods to either Britain or France because both sides were busy seizing American vessels.
Because this hurt US merchants, a lot of them were either defying the embargo or going to more remote European ports under wrong pretense-- as Lisboa was an Atlantic port and under British occupation because of the Peninsular War at the time, I'd imagine it was a prime candidate for that.
There's a reference to something like this in the book "Jefferson's English Crisis: Commerce, Embargo and the Republican Revolution" by Burton Spivak on page 162 (I'm citing this via a footnote in Peter Andreas' "Smuggler Nation: How Illicit Trade Made America", page 354):
Leonard Dupee White notes that one ship cleared from Boston to Charleston even blamed bad weather for having to veer off course and ending up in Lisbon: "On January 14, 1809, the schoner Charles cleared Boston for Charleston in ballast, but turned up in Lisbon. The master alleged that stress of weather had forced him 'bear away' for that distant port."
I'm guessing that your William Elwell had a similar story for how he ended up in Lisbon.