In 1896 Frobenius became aware of Cayley's 1858 Memoir on the theory of matrices and after this started to use the term matrix. Despite the fact that Cayley only proved the Cayley-Hamilton theorem for 2 × 2 and 3 × 3 matrices, Frobenius generously attributed the result to Cayley despite the fact that Frobenius had been the first to prove the general theorem.