At first he served in the Mediterranean as an ordinary seaman aboard the light cruiser HMS Coventry and saw action when his ship was torpedoed by an Italian submarine and dive-bombed.

[4] After the end of the war in 1945, he returned to his studies at Cambridge, graduating with First Class Honours in Classics Part II, with a distinction in his special subject, linguistics.

[4] While studying at Corpus Christi College, he attempted, with some of his fellow students, to use cryptographic methods to decipher the "Minoan Linear Script B".

[1] The men began to collaborate on the progressive decipherment of Linear B, writing Documents in Mycenean Greek in 1956, following a controversial first paper three years earlier.

Chadwick's philological ideas were applied to Ventris's initial theory that Linear B was an early form of Greek rather than another Mediterranean language.