Having drawn together a well armed force of seven hundred men, 370 of whom were cavalry, 170 musqueteers, and 160 armed with pikes, Vaca de Castro appointed captain Francisco de Carvajal serjeant major[10] of his army; the same person who was afterwards maestre de campo general under Gonzalo Pizarro.  Carvajal was an officer of great experience, having served above forty years in the army, and was bred in the wars of Italy under the great captain, having risen in that service from the ranks to a lieutenancy.  By him all the movements of the army were directed.

About this time a message was received by Vaca de Castro from Gonzalo Pizarro, who had just returned to Quito from his disastrous expedition to Los Canelos, formerly related.  Gonzalo made offer to the governor to march to his assistance with all the troops he could raise; but de Castro, in answer, after thanking him for his good will, desired him to remain at Quito and on no account to come to the army, as he had hope of bringing Don Diego to terms of accommodation, being only desirous of restoring the country to peace.  In this procedure, the governor meant in some measure to mortify the pride of Gonzalo Pizarro; and besides, he feared lest his natural desire of taking revenge for the murder of his brother might prove an invincible obstacle against Don Diego agreeing to any accommodation, who would never venture to submit to any one who was accompanied by Gonzalo Pizarro, whose friends in the royal army were very numerous.  Some persons allege that Vaca de Castro was afraid of permitting Gonzalo to join the army, lest they might elect him as their general, as he was greatly beloved by the soldiers.  At this time likewise, Vaca de Castro sent orders to those persons who had the charge of the children of the late marquis in San Miguel and Truxillo, to remain with them there till farther orders, and on no account to carry them to Lima; alleging, as a specious pretext, that they were safer there than at Lima.

All his military preparations being completed, Vaca de Castro left Jauja with his army in excellent order, taking the route for Guamanga, as he was informed that Don Diego was in full march to take possession of that city, or to take post at a very important passage of a river in that neighbourhood, which would give great advantage in the future operations of the war to either party which might obtain possession of that post, as Guamanga was surrounded by precipitous rocks and deep vallies, serving as natural fortifications of extremely difficult access.  Captain Diego de Royas, who has been formerly mentioned as commanding the advanced guard of the royal army, had already occupied the city of Guamanga; and on receiving intelligence of the rapid march of Don Diego to that place, had fortified himself there as strongly as possible, that he might be able to defend it till the arrival of the army under Vaca de Castro.  The governor, therefore, marched with as much celerity as possible,