The Republican forces consisted only of the Tabasquian militia from the surrounding areas ranging between 300 and 1,100 men, only half of whom were equipped with firearms the others fought with machetes.

[1]: 20–21 On January 1, 1864, Don Pedro Fuentes along with three dragoons broke into the Esquipulas church and rang its bells in defiance to the enemy fire, and following a brief shootout, returned unharmed to his camp.

[1]: 23–24 At three in the morning on the 14th the Zaragoza section (the right), waded through a forest track to arrive directly on the left flank of the main square, taking positions in the La Punta district, the companies 1st, 2nd "Hidalgo" and auxiliaries from Juchitan, marched to join the Valle section in Tierra Colorada, which would occupy the bottom of the street Loma de los Perez, which was at the French right flank.

The events quickly turned against the defenders whereas the cavalry company completely disrupted the Imperialist garrison, four soldiers and commander Castillo were left dead, nine taken prisoners, including an officer, who was condemned to death by martial laws.

[1]: 27 The Imperialists concentrated the defense of San Juan Bautista around the "Principal" and the Governor's House that were barricaded and perforated with loopholes from top to bottom.

The house north of the market, which had walls pierced with loopholes onto the Esquipulas Street was occupied by the Republican center.

[1]: 27–28 The first defense line was formed by buildings and trenches, with the exception of the Romano tradehouse on the Aurora street, which was equipped by light weapons.

[1]: 29  The Republican Army fully sealed the siege on the town starting from January 18 and installed five of the smaller culverins and two 24 pounder cannon around San Juan Bautista.

[1]: 39–42 As the "Casa Fuerte" remained the last resort of the defenders right at the river, the Republicans decided to attack with heavy artillery from the hill of the Encarnación.