In CRYPTO '94, Langford and Hellman attacked DES reduced to 8-round in the chosen plaintext scenario by their "differential-1inear cryptanalysis," which is a combination of differential cryptanalysis and linear cryptanalysis. In this paper, a historical review of differential-linear cryptanalysis, our formalization of differential-linear cryptanalysis, and the application of differential-linear cryptanalysis to FEAL-8 are presented. As a result, though the previous best method (differential cryptanalysis) required 128 chosen plaintexts, only 12 chosen plaintexts are sufficient, in computer experimentations, to attack FEAL-8.