In late March 1521, the royalist side moved to combine their armies and threaten
Torrelobatón, a rebel stronghold. The
Constable of Castile began to move his troops (including soldiers recently transferred from the defense of Navarre) southwest from Burgos to meet with the
Admiral's forces near
Tordesillas. This was possible due to the comunero-aligned Count of Salvatierra's force being caught up in the siege of
Medina de Pomar; the Count's forces had previously been enough of a threat to force the Constable to maintain a large army to defend Burgos. The Constable's army had approximately 3,000 infantry, 600 cavalry, 2
cannons, 2
culverin, and 5
light artillery pieces. His army took up positions in
Becerril de Campos, near
Palencia. Meanwhile, the comuneros reinforced their troops at Torrelobatón, which was far less secure than the comuneros preferred. Their forces were suffering from desertions, and the presence of royalist artillery would make Torrelobatón's castle vulnerable. They had two strategic possibilities: prevent the Constable and Admiral from uniting their forces by striking at the Constable while he was still on the field, or carry out low-level harrying operations to try to slow the Constable down. The comuneros did neither, and thus allowed the Constable to approach nearly unchecked. The commander of the comunero armies,
Juan de Padilla, considered withdrawing to
Toro to seek reinforcements in early April, but wavered. He delayed his decision until the early hours of 23 April, losing considerable time and allowing the royalists to unite their forces in
Peñaflor. ==Battle==