At the head of a combined army, Sucre then marched against the Royalists, who under Aymerich were descending the mountain slopes from Quito, in two separate columns. One of these columns he totally defeated at Yahuachí on the 19th August, and compelled the other, which was led by Aymerich himself, to return to Quito with heavy loss. He then ascended the slopes of Chimborazo and occupied the plateau of Ambato, but was here attacked by Colonel Gonzalez with very superior forces, and was completely defeated, with a loss of 300 killed and 640 prisoners. He himself was wounded, and returned to his former position with a remnant of his force. Here he was fortunately reinforced by a battalion of 500 Columbian infantry, and as Aymerich did not follow up the victory, held his ground, till on the 20th November he arranged an armistice of ninety days.
At this time the Royalists, whose total force of regular troops amounted to 3,000 men, in the Provinces of Cuenca, Quito, and Pasto, received a reinforcement of 800 men, under General Murgeón, who had been appointed Viceroy of New Granada on the death of Sámano. Murgeón had arrived from Europe at Puerto Cabello with a smaller force, which being increased by La Torre, he led across the Isthmus to Panama, whence he went by sea to Atacames, and from there marched for sixty miles through a dense forest and then over the Cordillera to Quito, where he arrived on the 24th December, 1821, and took the command.
When New Granada was secure, Bolívar wrote to O'Higgins that:—"The Army of Columbia was about to march on Quito with orders to co-operate with the Argentine-Chileno Army in their operations against Lima," but after that, affairs in the North distracted his attention. After the fall of Cartagena, he wrote to San Martin, proposing to take 4,000 men across the isthmus, and by sea to Peru, to aid him in crushing the Royalists in the centre of their power, leaving them in their positions on the equatorial Andes till afterwards. But the defeat suffered by Sucre,
