Excerpts from Books and Wikipedia
"Sparta was no longer the dominant city in the Achaean League, its old association, and the other cities of the League had been running roughshod over it. Unhappy with a League decision, Sparta announced its intention to appeal directly to Rome (now tacitly recognized as the real power on the Greek peninsula). . . . In response, a Roman fleet sailed for Greece, where a force of twenty-six thousand men and thirty-five hundred cavalry, under the command of the consul Mummius, pitched camp at the Isthmus of Corinth. Some of the Achaean League cities tried to fight back, under the command of a Corinthian general, but the Greek army soon broke; the Corinthian commander fled, and then poisoned himself; the defeated Achaean League soldiers ran to Corinth and hid in the city. Mummius set the city on fire, and Romans overran it. Rome had finally swallowed Greece." [Bauer: Ancient World, p. 660-1]