Juan José Holzinger, a German soldier of fortune in the Mexican army during the Texas Revolution, was born Johann Josef Holzinger in the vicinity of Mainz, Germany. Most of the details of his life before his appearance in Texas are known from conversations he had with Herman Ehrenberg in 1836, which Ehrenberg later recorded in the narrative of his own adventures in Texas, Texas und seine Revolution (1843). Holzinger went to Mexico from Germany about 1825 as an employee of the British mining company Real del Monte. His engineering skills allegedly attracted the attention of Gen. Antonio López de Santa Anna, who hired him to build the house on Santa Anna's hacienda, Manga de Clavo, and afterwards made him an officer of engineers in the Mexican army. By 1832, when Santa Anna was leading a Federalist revolt to overthrow the Centralist government of Anastasio Bustamante, Holzinger was a captain of engineers in Santa Anna's rebel army.
Holzinger entered Texas from Matamoros in mid-February 1836 as a lieutenant colonel of engineers and commander of the artillery in the army of Gen. José de Urrea. In two separate engagements between Urrea's forces and the Texans, one at Refugio and another at Victoria, Holzinger saved the lives of Texan prisoners. At Refugio two German Texans captured among Capt. Amon B. King's men escaped execution through Holzinger's intervention, and at Victoria he saved the lives of twenty-six of Lt. Col. William Ward's troops by pretending to need them to transport cannons across the San Antonio River. Later, on March 20, at the battle of Coleto, Holzinger was one of the three officers sent by General Urrea to negotiate the surrender of Col. James W. Fannin, Jr., and his forces. Some of the Texans later contended that Urrea had signed a document of capitulation promising them and Colonel Fannin all consideration due them as prisoners of war, but Urrea later denied this allegation in his published diary of the Texas campaign. However, in his formal statement concerning the affair, written in captivity on June 3, 1836, to John A. Wharton, Holzinger affirmed that Urrea's secretary had been ordered to draw up the surrender in Spanish and in English. Holzinger was also present at Goliad during the incarceration of the Texan prisoners there, but had no part directly in the Goliad Massacre on March 27. Indeed, according to Ehrenberg's account, Holzinger had just two days earlier offered amnesty to all the Germans among the prisoners in return for service in his artillery unit, but the offer was unanimously refused.
After the massacre Holzinger went with Urrea to Matagorda, where on April 14 the general left him with orders to begin constructing fortifications. When news of Santa Anna's defeat at San Jacinto reached Matagorda, Holzinger attempted to flee to Matamoros, but was soon captured and delivered to the headquarters of the Texas government at Velasco by some of his former Texan captives, among them Ehrenberg. Within a few days of his arrival at Velasco, however, Holzinger was released with the gratitude of the Texas government for his generous treatment of the Texan prisoners who had fallen into his hands. From Texas Holzinger sailed aboard the Pennsylvania for New Orleans, where he landed on June 22. He later returned to Mexico, where, in the state of Vera Cruz, probably in the vicinity of Puente Nacional, he owned thirty leagues of land. It is not known how long continued to serve in the Mexican army. He died on May 9, 1864, and was buried in Mexico City.