they sank the cruise ship because the thought it was carying aminition.
Perhaps you're thinking of the liner Lusitania which was sunk by German submarines during World War One.
Lusitania wasn't a German submarine, it was an American merchant ship that was sunk by German submarines.
There is no ship known, it is not the Lusitania, which was an English ship.
Athenia
One of the main reasons that Us joined the war was due to there cruse ship being shot down by some of German submarines
German military submarines were called U-boats, which is short for unterseeboot. This means just 'undersea boat.'
In the World War One era, it was vital for cargo ships to cross the Atlantic Ocean for the transport of supplies from the USA to Western Europe. The major danger in this was that German submarines were able to use torpedoes to sink ships, both military and merchant vessels. The ship sailing formation called a convoy was designed to protect ships in the convoy and to destroy German submarines.
The sinking of the civilian ship Lusitania by a German U-boat (submarine) which had US civilians on it angered them to becoming involved against the Germans.
This would be a convoy. They were limited to the speed of the slowest ship. They used a zig zag pattern to make it difficult for the submarines to get a firing solution against them.
There were no facilities in Argentina for German U-Boats (at least not discovered yet). I have read that German submarines in the South Atlantic that were in need of fuel would approach the Argentinian coast and radio asking for fuel. Then a transport ship would take the fuel to the submarine.
German Embasy gave a warning to US that any ship that is seen and is in British side, will be atacked by German submarines without warning.
They are called submarines