User blog comment:Argorrath/Treyarch posts a message of zombies; possibly hinting to a DLC 4/@comment-5134053-20130801051305

1. World War 1 (indicated by 1917 and Northern France)

2. Old Crew

>Dempsey: Calling Germany Fritz, a common nickname for Germans in WW1 and 2

>Takeo: Mentioning the Emperor and Japan

>Belenski: Saying the Motherland

>Richtofen or Groph: the "Doctor" is mentioned