HMHS Britannic, the largest - and grandest - of the Olympic Class cruisers, sister ship to the ill-fated Titanic, was launched just six months before the outbreak of WWI and was soon pressed into service as a floating hospital. On Nov. 21, 1916, steaming between Greek islands, an explosion ripped through her and in less than an hour she was four hundred feet beneath the waves. Thirty men lost their lives.