After the Battle of Portada de Guías and the occupation of Lima by the United Restoration Army under the command of General Manuel Bulnes, 700 men from the Ayacucho battalion led by General Domingo Nieto had retired to the Callao fortress, who joined the Real Felipe garrison, composed of by 500 soldiers under the command of Colonel Manuel de la Guarda.

[5] His figure was reduced however to a semi-prisoner of the men who defended the port, with mere freedom to speak and write negatively against the Restoration Army and Santa Cruz.

[6] The site of the square was limited to a medium-effective siege by land and sea since the restorers did not have the men and materials necessary to undertake an assault on the fortress where the Confederate troops were garrisoned.

As the besieging army was camped in a marshy and unhealthy area, the casualties due to illness were numerous, which together with the constant departures of the garrison under the command of Colonel de la Guarda made an effective siege difficult.

From the sea, Chilean gunboats commanded by the English attacked Callao only at night; always after midnight we contemplated the moving spectacle of the numerous incandescent bullets crossing the darkness [...] The cavalry combats of the outposts and the exits of the besieged were small, the besiegers did not think of taking the Fortress by assault since for this they would have had to gather their entire army.On the other hand, Colonel de la Guarda, whom the Chilean historian Francisco Antonio Encina describes as energetic, was not content with harassing the besiegers by land and the garrison having been unable to fire their cannons on the Chilean ships due to a direct threat from those of the ships' willingness to open fire on them if their ships were damaged in the firefight.

He did not waste any opportunity to attack them with whatever means were within his reach, von Tschudi himself refers to an episode he witnessed while on board the neutral merchant ship Edmond.

Adding to the pressure, the annoyances of foreign powers such as Great Britain, France and the United States that prevented an effective blockade and siege of the port.

For his part, the Chilean historian Gonzalo Bulnes points out that "Although the picture of the deprivations of the besieging division, will not go down in history adorned with the brilliant colors of Buin or Yungay, the integrity with which they endured their sufferings and energy will be always worth remembering.

The plan now was to advance north of Peru to the provinces that were loyal to him and force the Confederate army to go in pursuit and thus give a decisive battle in positions more favorable to it.