Meanwhile the guerilla chiefs farther down the Orinoco made headway against the Spaniards, and the whole plain turned to the patriot side. Hearing of these successes, Bolivar resolved to return to Venezuela. He landed near the mouth of the Orinoco, but was soon driven thence and took ship for Ocumare, near Puerto Cabello. From this point he sent a small expedition inland towards Valencia under the command of MacGregor, who achieved some successes against isolated bodies of loyalists, was joined by many llaneros, and finally made his way to the plains of Barcelona, while Bolivar was compelled to re-embark and flee to Hayti. MacGregor took the city of Barcelona, and then with the assistance of the negro chief, Piar, who had been besieging Cumana, repulsed Morales himself at the battle of Juncal. By the end of 1816 the patriots had gained so many advantages that Morillo thought himself obliged to return to Venezuela at the head of huge reinforcements. However, the patriot cause needed a head. The chieftains were rude and ignorant men with a talent for fighting and nothing more, while Bolivar was a man of wide and varied accomplishments. In spite of his failures he retained great prestige among the Creole officers. He was agreed upon as general-in-chief, and in December landed at Barcelona. But Piar had led his victorious army over to the Orinoco, and notwithstanding Bolivar's entreaties the llaneros persisted in their refusal to return to a country where cavalry could not manoeuvre to advantage. When Bolivar arrived at Piar's headquarters near Angostura he appreciated that the true theatre for a successful war had been found. In those plains the llanero cavalry, which formed the bulk of the patriot force, was invincible. Morillo also realised that the coast would not long remain tenable if the line of the Orinoco were in the hands of the patriots, and he sent a regular force of three thousand men under La Torre down the Apure and Orinoco to Angostura, while he himself quickly made an end of the few insurrectionists who stubbornly refused to retire from the coast to the llanos. During one of Bolivar's absences, La Torre offered Piar battle, and at San Felix, in April, 1817, the plainsmen annihilated the Spanish infantry. [Illustration: THE PASS OF ANGOSTURA, BOLIVAR CITY.]