These merchantmen are KNOWN to be sunk by Japanese submarines during WWII off the US West Coast (there are several others sunk by explosions, but cannot be verified as sunk by submarines):
Germany violated the neutrality of the US by attacking merchant ships that were plying the Atlantic routes. German U-boats used to torpedo down merchant ships in order to frustrate trade and the movement of raw materials between US and UK.
Swinaton Bay
They attacked British merchant ships
german u boats were sinking us merchant ships
The operation to protect American merchant ships in the Atlantic before the US entered the war was called the Neutrality Patrol. It involved escorting and protecting merchant ships from attacks by German submarines.
stopped sailing ships in the Mediterranean sea
We entered World War 1 because of a German submarine attack on U.S. merchant ships in 1917.
They started to steal from US merchant ships
The Hawaiian Islands were important to U.S. naval and merchant ships because they stopped at Hawaii on their way to East Asia.
Whenever they became a target of opportunity.
'42 thru '44.
When ever they were presented with targets of opportunity.