The second phase of the war spanned the years 1824 to 1828. When a counteroffensive by the Porte overcame the feuding Greek forces in 1825, the rebels lost the advantage they had gained in the first phase. In the mid- to late 1820s, the sultan enlisted the assistance of Mahomet Ali, the ruler of Egypt, to launch a twopronged attack. The sultan's forces marched from the north while the army of Mahomet Ali established a base at Messini on the south shore of the Peloponnesus and then advanced northward. Caught between two superior forces, the Greek armies relinquished all the gains made in the first years of the war. The fall of the fortress at Mesolongion in the spring of 1826 gave the Ottoman forces control of western Greece and of the Gulf of Patras; the fall of Athens later that year restored all of central Greece to Ottoman control. At that point, with the Balkan conflagration close to extinction, the powers of Western Europe intervened.