Finall Answer:
The plaintext message is: "defend the castle invade the region."
Step-by-step explanation:
A Caesar cipher involves shifting each letter in the plaintext message by a fixed number of positions down or up the alphabet. With a key of 2, each letter is shifted two places backward in the alphabet to decipher the message.
Starting with the encrypted text:
"d -> b, e -> c, f -> d..." and so on, applying this backward shift reveals the decrypted message as "defend the castle invade the region."
This decryption method works by substituting each letter in the ciphertext with the letter that is two positions behind it in the alphabet. By following this consistent shift for each letter in the encrypted message, the original plaintext is revealed.