What is the name of the third "unsinkable ship" in the 1910s?

I already have the Titanic and the Lusitania, but I can't remember the last one or seem to find it on the internet. PLEASE HELP!!!! I need this by the end of second hour! First one to give me the answer gets 10 points :P

What is the name of the third "unsinkable ship" in the 1910s?
Britannic
Reply:Actually, I don't think the Lusitania was ever deemed "unsinkable". Titanic was however, due to her water-tight compartments. Her sister ships, Brittanic and Olympic, also had the same water-tight compartmentalization. Of course, both the Titanic and Brittanic were sunk thus disproving their theories of unsinkability. The Olympic survived for quite awhile (1937 I think) before finally being scrapped.