His father, Francisco Antonio Zumalacarregui, was a lawyer who possessed some property, and the son was articled to a solicitor.
But Zumalacarregui, who was noted for his grave and silent disposition and his strong religious principles, disliked the disorderly life of the guerrillas, and when regular forces were organized in the north he entered the 1st battalion of Guipuzcoa as an officer.
Zumalacarregui had no sympathy with the liberal principles which were spreading in Spain, and became noted as what was called a Servil or strong Royalist.
The recommendation was not acted on, but Zumalacarregui knew of it, and laid up the offence in his mind.
Died in 1833, Zumalacarregui was marked out as a natural supporter of the absolutist party which favoured the king's brother, Don Carlos.
In a few months Zumalacarregui had organized the Carlist forces into a regular army.
The pretender was, however, a narrow-minded, bigoted man, who regarded Zumalacarregui with suspicion, and was afraid of his immense personal influence with the soldiers.
Zumalacarregui had therefore to drag behind him the whole weight of the distrust and intrigues of the court.
If Zumalacarregui had been allowed to follow his own plans, which were to concentrate his forces and march on Madrid, he might well have put Don Carlos in possession of the capital.
But the court was eager to obtain command of a seaport, and Zumalacarregui was ordered to besiege Bilbao.
Zumalacarregui was a fine type of the old royalist and religious principles of his people.
An engaging account of Zumalacarregui will be found in The Most Striking Events of a Twelvemonth Campaign with Zumalacarregui in Navarre and the Basque Provinces, by C. F.
A chap-book called Vida politica y militar de Don Tomas Zumalacarregui, which gives the, facts of his life with fair accuracy, is still very popular in Spain.
At times he showed qualities as a guerillero quite equal to those of the Carlists, like Zumalacarregui and Cabrera, by his daring marches and surprises.