Born at El Puerto de Santa María in Cádiz, Juan Guilloto worked at a sawmill before joining the Spanish Army.

[8] At the end of August, he moved to the province of Toledo, where he led a battalion, trying to contain the Franco advance towards Madrid.

It was distinguished especially in the fights with the troops of the Army of Africa along the Tagus river during their advance towards Madrid, highlighting his interventions in Talavera, Santa Olalla, Toledo or Illescas.

During the fighting in the Talavera-Santa Olalla area, he revealed himself as an authentic military chief by coordinating the actions of the militias and regular units (Guardias de asalto) under his command.

During World War II, he served with the Red Army and the Bulgarian Communist forces.