You asked “Has anyone ever investigated the possibility that any of them had been sunk by a U-Boot?”

The answer is “yes” — Yves and I, along with Oliver and Simon have indeed looked at the possibility that any of those might have been sunk by a U-boat. I, for example, have a page in my personal databse of missing ships. It includes 220 or so missing steamers, of which about 65 are now known to have been sunk by U-boat. Very few of the rest remain viable candidates to have been sunk by U-boat. A few were lost to mines, mainly in the North Sea but most simply sank during storms.

INIZIATIVA, for example, is one of four old, small steamers that disappeared after sailing from Swansea or Barry on November 10 or 11, 1915 — and the weather chart for the next day is horrible.

What happened to MONTE CARMELO is pretty clear — look up Atlantic Hurricane Two of 1916 and compare locations.

I'm aware of the ANNA M. and ST. JOSEPH (which, I think, is the same vessel as your SAN GIUSEPPE) but don't have an answer for either vessel's disappearance currently. I hadn't heard of ESPERO before but will have a look and see what I can figure out.

Can't do much with ANGELO FERRARA without a date.

Best wishes,
Michael