What term refers to the most carefully guarded secrets of the war as deciphered from German translations?

The term that refers to the most carefully guarded secrets of the war as deciphered from German translations is "Ultra secrets." This designation originates from the intelligence breakthroughs during World War II when the Allies managed to decrypt highly classified communications, particularly those of the German military. The success of deciphering these messages provided critical insights into enemy strategies, troop movements, and operational plans.

"Ultra" specifically referred to the intelligence derived from the decryption of the Enigma machine, which the Germans used to encode their communications. The information gained through these ultra secrets played a significant role in many battle decisions, significantly impacting the outcome of the war.

The other options pertain to different concepts within military and intelligence contexts. Firing tables are used for artillery to calculate the trajectory and range of projectiles. Electronic codes refer more broadly to encoding methods used in electronic communications, while strategic plans encompass a wide range of military strategies and operations without specifically tying them to decrypted intelligence.