The Costa Ricans marched to Rivas, and as they approached Walker retired on the Transit company's lake steamers to Granada. Two columns of 300 each dislodged on the 7th of April the Nicaraguan garrisons left by Walker in La Vírgen and San Juan del Sur, and on the following day the rest of the army occupied Rivas. But Walker soon came upon them. Under cover of the thick plantain and cacao plantations, he entered unperceived in the morning of the 11th. His attack began about 8:30 and lasted till night. He captured the main plaza, and from the church and houses kept up a deadly fire on the enemy, stationed only two blocks away. The latter fought desperately, till Walker, finding himself closely pressed by Costa Rican reënforcements from La Vírgen and San Juan del Sur,[XVI-66] and surrounded by burning buildings, gave orders for retreat, which was silently effected under cover of the darkness, never tarrying till he reached the Gil Gonzalez River. He left behind a considerable number of rifles, revolvers, and other arms, and about 50 saddled horses, besides his seriously wounded in the church. The Costa Rican victory was complete, though at the expense of heavy casualties.[XVI-67] The victors were relentless toward the first prisoners that fell into their hands. According to Mora's report, the wounded in the church were bayoneted, and seventeen others shot. Walker tried to make out that he had won a great victory, and the event was celebrated in Granada with salutes and ringing of bells; and his government published that the Costa Ricans had been dispersed and were in full flight.[XVI-68] [Sidenote: UNSTABLE POWER OF THE PIRATE.] Mora expected heavy reënforcements from Punta Arenas, and had formed the plan, after securing eastern Nicaragua between the Pacific and the great lake, and cutting off the transit communication, already suspended by a general order, to assail Walker in his stronghold of Granada. He was further encouraged in this by news that forces of Salvador and Honduras were already on the western frontier, under Belloso and Xatruch, ready to coöperate with him. But the breaking out of cholera in his army, with terrible havoc in its ranks, necessitated the abandonment of the project for the time. And a report having come of plottings in Costa Rica against his authority, with his brother José Joaquin and his personal staff, he returned home, leaving General Cañas in command of the remnants of the army, with orders to send it back to Costa Rica in the most convenient manner, which was done, many of the men being left dead or dying on the march. Cañas found it unavoidable to leave his wounded and sick in Rivas, and fearing retaliation because of the executions of prisoners at Santa Rosa and Rivas, he wrote Walker on the 26th of April, recommending these men to his protection, and proposing an exchange of prisoners, of whom he had twenty, according to the usages of war. This letter had the desired effect.[XVI-69] CHAPTER XVII.