Maestro de Campo was a rank created in 1534 by the Emperor Carlos V

Charles V, Holy Roman Emperor

Charles V was ruler of the Holy Roman Empire from 1519 and, as Charles I, of the Spanish Empire from 1516 until his voluntary retirement and abdication in favor of his younger brother Ferdinand I and his son Philip II in 1556.As...

, inferior in rank only to the Capitán General and acted as a chief of staff. He was chosen by the monarch in the Council of State, and commanded a tercio

Tercio

The tercio was a Renaissance era military formation made up of a mixed infantry formation of about 3,000 pikemen, swordsmen and arquebusiers or musketeers in a mutually supportive formation. It was also sometimes referred to as the Spanish Square...

. Their powers were similar to those of the old Marshal

Marshal

Marshal , is a word used in several official titles of various branches of society. The word is an ancient loan word from Old French, cf...

s of the Kingdom of Castile

Kingdom of Castile

Kingdom of Castile was one of the medieval kingdoms of the Iberian Peninsula. It emerged as a political autonomous entity in the 9th century. It was called County of Castile and was held in vassalage from the Kingdom of León. Its name comes from the host of castles constructed in the region...

: he had the power to administer justice and to regulate the food supply. His personal guard consisted of eight German halberdiers, paid by the king, who accompanied him everywhere. Immediately inferior in the chain of command was the Sargento Mayor

Sargento Mayor

Sargento Mayor was a rank immediately below that of Maestro de Campo in the Spanish tercios of the 16th and 17th centuries. Initially second in rank to a Coronel in a Colunella, the Sargento Mayor became second in rank to the Maestre de Campo after the creation of the tercios in 1534...

. One of the most famous Maestro de Campo was Julian Romero, a common soldier who reached the rank of Maestro de Campo and that brought victory to the Spanish tercios in the battles of San Quintín

Battle of St. Quentin (1557)

The Battle of Saint-Quentin of 1557 was fought during the Franco-Habsburg War . The Spanish, who had regained the support of the English, won a significant victory over the French at Saint-Quentin, in northern France.- Battle :...

 and Gravelines

Battle of Gravelines (1558)

The Battle of Gravelines was fought on July 13, 1558 at Gravelines, near Calais, France. It occurred during the 1547–1559 war between France and Spain....

.

In the overseas colonies of the Spanish Empire

Spanish Empire

The Spanish Empire comprised territories and colonies administered directly by Spain in Europe, in America, Africa, Asia and Oceania. It originated during the Age of Exploration and was therefore one of the first global empires. At the time of Habsburgs, Spain reached the peak of its world power....

a governor held the rank of Capitán General over his local forces and would appoint his Maestro de Campo.