During the First World War, many hospital ships were attacked, sometimes deliberately and sometimes as a result of mistaken identity.
Investigators from neutral countries like Spain were allowed to inspect hospital ships to confirm that Article Four wasn't being violated.
[4] Even with the inspections from neutral countries the German High command alleged that hospital ships were violating Article Four by transporting able-bodied soldiers to the battleground.
[4] The biggest hospital ship sunk by either mine or torpedo in the First World War was Britannic, the sister of Olympic and the ill-fated Titanic.
Britannic hit a mine on November 21, 1916; 30 people were killed, but the rest of the crew and passengers were able to escape.