Pretty much just the title. The Vaterland, for example, was an ocean liner that was referred to as a “he”, instead of a “she”. (For instance, the Titanic was a she.)
You are asking "why", but this did not happen. The grammatical rules did not change. Maybe you are confused by the German grammar?
If a ship is introduced only by name, it is feminine: The "Fatherland" was built in 1913. She was scrapped in 1938. In German: Die "Vaterland" wurde 1913 gebaut. Sie wurde 1938 verschrottet.
If it is introduced by type, the gender is given by that type: The steamer "Fatherland" ... in German: Der Dampfer "Vaterland" wurde ... Er wurde 1938 verschrottet.
Also the feminie genitive article is "der" -- the captain of the "Fatherland" in German: der Kapitän der "Vaterland"