The person that is credited with designing the architecture is named John Von Neumann.

If you're thinking of the stored program concept it wasn't Von Neumann, but it's a common misconception. Von Neumann himself credited Turing for it. Independently, the concept was described in a patent application by Konrad Zuse as early as 1936.

How did Germany contribute to computers?

Zuse is widely considered the inventor of the modern computer because of his Z3 model. It never achieved recognition during the war she went largely unnoticed, not even being used by the government in secrecy like the British Colossus.

For the longest time the British early computers went unknown too during the secrecy, we only credit them today because they were eventually declassified.

American computers enjoyed the largest recognition during the '40s. The ENIAC is probably the most widely known and had a major contribution to the world of computing not only because it proved the concept of a general purpose computer, but also because its creators held the Moore School Lectures which taught the ENIAC design principles.

Another very important computer was the ABC, but not for its design (it wasn't Turing complete) but for an indirect reason: its patent on the design of a computer was challenged and invalidated in the landmark case Honeywell v Sperry Rand which resulted in the modern electronic computer entering public domain, which was an enormous boost for the industry.