Actually, with that particular message, ~~frequency analysis~~ incidence of coincidence will help immensely, to the point of making it easy to solve.
With a modern block cipher, a partial key doesn't help. If you have 120 bits of a 128 bit AES key or whatever, decrypting the cipher text with your partial key will give pure noise. Even if you flip just one random bit in the key, the decrypt will be indistinguishable from complete randomness. Not so with Enigma; if you have parts of the key correct, parts of the rotor settings correct, parts of the wheel selection correct, patterns in the plaintext will show up as patterns in the ciphertext. The more of the key you have, the more those patterns will show up when you run the decryption routine against the ciphertext.
Natural language has a quirk where letters are more likely to be repeated. If you calculate the percentage of letters that are repeated, this gives you the incidence of coincidence. Incidence of coincidence is preserved by a partial Enigma key. So in that particular plaintext, all those repeated UUUs, those repeated NN, those XX and TT, those will light up like quasars.
Incidence of coincidence analysis should just tell you outright what all of the rotor settings are. From then you'll need someone familiar with German and the code language to be able to figure out the plugboard settings, but that's not as difficult as you might think.
With a modern block cipher, a partial key doesn't help. If you have 120 bits of a 128 bit AES key or whatever, decrypting the cipher text with your partial key will give pure noise. Even if you flip just one random bit in the key, the decrypt will be indistinguishable from complete randomness. Not so with Enigma; if you have parts of the key correct, parts of the rotor settings correct, parts of the wheel selection correct, patterns in the plaintext will show up as patterns in the ciphertext. The more of the key you have, the more those patterns will show up when you run the decryption routine against the ciphertext.
Natural language has a quirk where letters are more likely to be repeated. If you calculate the percentage of letters that are repeated, this gives you the incidence of coincidence. Incidence of coincidence is preserved by a partial Enigma key. So in that particular plaintext, all those repeated UUUs, those repeated NN, those XX and TT, those will light up like quasars.
Incidence of coincidence analysis should just tell you outright what all of the rotor settings are. From then you'll need someone familiar with German and the code language to be able to figure out the plugboard settings, but that's not as difficult as you might think.