It is noteable as it hints that the original Wolfenstein (or at least Escape From Wolfenstein and Eisenfaust) occurred before Return to Castle Wolfenstein. It also mentions that the war was thought to have been over after his mission (a reference to the attempt on Hitler most likely). The letter itself breaks the 4th wall, speaks to the 'player' and talks about platforms, chatrooms, and rumors of a 'rebirth', return, etc, concerning the series as a 'game'.
In the PS2 Operation resurrection and XBox Tides of War guides reduced the introduction down to the first paragraph (again suggesting it as a 'sequel' to the original).
- It’s been a long time. The dust has long settled, and the castle is a gray smear in the back of your memory. You’ve forgotten what you used to know so well. The corners and secret walls, the shouts and shots are all a blur—no sharp images remain in your mind. You thought the war was over. It seemed as if Castle Wolfenstein would recede into the mists of time, a legend, never seen but often mentioned. That is, until today.
However, Tides of War itself unlocks Wolfenstein 3D as a 'second campaign', and Wolfenstein 3D Classic also places it after RTCW.
Welcome Back, SoldierEdit
OSA Operation Return to Castle Wolfenstein 14, Jul, 1942 Top Secret
Welcome Back, Soldier It's been a long time. The dust has long since settled and the castle has been a gray smear in the back of your memory. You've forgotten most of what you used to know so well. The corners and secret walls, the shouts and shots are all a blur — no sharp images remain in your mind. You thought the war was over. It seemed as if Castle Wolfenstein would simply recede into the mists of time, a legend, never seen but often mentioned. The one, they say, that started it all. Some of us try to remember it from experience: the colors, the shapes, the sounds. Most only hear tales, see pictures here and there, listen to those who lived through it, and watch its inspired descendants. It was the granddaddy, establishing a lineage that spread across every platform and has no end in sight. Yet you thought it was gone. Then came the rumors, the speculation, the hopeful whispers on boards and chat rooms. It might happen, the dust was being swept away, the stories were being retold. There could be a rebirth. There would be a return. Now the waiting is over and you've got it. It's loading as you read this, taking longer than you expected, but that's good. Each minute means more that you get to explore, more challenges that you'll face. You're guessing what might be in there, what you might find. You'll never know, however, until you Return to Castle Wolfenstein. Welcome back, Solider. It's been a long time.