A 'Titanic' curse that sank its sister ship

Most people are familiar with the story of the Titanic and its tragic sinking (thanks to Leonardo DiCaprio and Kate Winslet), but the sinking of its sister ship Britannic remains largely unknown.

The White Star Line shipping company had built three major 'Olympic grade' ocean-liners, of which HMHS Britannic was the final creation, as per Mark Chirnside in his book The Olympic Class Ships: Olympic, Titanic, Britannic. The first ship, the RMS Olympic, was the world's largest ocean-liner from 1911 to 1913 -- the crown was taken briefly during that tenure by the RMS Titanic in 1912.

Launched before the commencement of the First World War, the Britannic was the largest out of the three Olympic liners and served as a hospital ship. The ship was shaken by an explosion most likely from a naval mine and sunk near the Greek island of Kea at 8:21 am on Nov. 21, 1916. It was initially intended to serve as a passenger ship before being put to use as a hospital ship during the World War.

After the Titanic was wrecked by an iceberg, the builders modified Britannic and made design changes due to lessons learned from the sinking. The latter was considered to be their safest ship. 'Large crane-like davits - or safety arms' holding six lifeboats each were installed in the ship, said a report in The Sun. The hull's design was changed to make it less susceptible to icebergs, according to History.com.

After the explosion, the Britannic took just 55 minutes to sink completely, which was faster than the Titanic. The disaster killed 30 people, most of whom were in prematurely launched lifeboats and got sucked in by the fast-moving propellers of the ship. Water also gushed in from portholes that were open to allow air into the sick wards. In all, 1,035 survivors were rescued from the water and lifeboats.

In 1976, ocean explorer Jacques Cousteau found the Britannic lying on its side 400 feet below the surface of the Aegean Sea. The vessel is the largest passenger ship on the sea floor. It was also the largest ship lost in the First World War. Britannic had completed five successful journeys before its final voyage.