The Battle of Thymbra was the decisive battle in the war between Croesus of the Lydian Kingdom and Cyrus the Great of the Achaemenid Empire. Cyrus, after he had pursued Croesus into Lydia after the drawn Battle of Pteria, met the remains of Croesus' partially-disbanded army in battle on the plain north of Sardis in December 547 BC. Croesus' army was about twice as large and had been reinforced with many new men, but Cyrus still utterly defeated it. That proved to be decisive, and after the 14-day Siege of Sardis, the city and possibly its king fell, and Lydia was conquered by the Persians.