RMS Britannic was the third and final of the Olympic-class ocean liners. It was under construction at the time of Titanic's sinking, which greatly influenced the many design changes between the two. Construction was wrapping up by 1914, but World War 1 broke out and required the ship to be drafted into the war as a royal hospital ship.
HMHS Britannic struck a German mine on the coast of Greece while serving as a hospital ship on November 21, 1916. It sank in 55 minutes and suffered 30 deaths, all from a lifeboat that got caught in a still-turning propeller. The sinking was largely due to many portholes being left open, which was a violation of company policy but the Greek heat led to nurses breaking it.
HMHS Britannic was the third and final of the Olympic-class ocean liners. It was the only Olympic-class ocean liner to never be the largest ship in the world. It never served as a passenger ship, instead spending its life as a Royal hospital ship until it was strunk by a mine and sank in 1915.