Hungary, enriched by renewed Western cultural influences from Italy and France under the rule of Angevin king Charles I, once more becomes a significant power in central Europe.
Charles’s successful foreign policy, based on strong ties with Poland, has resulted in the extension of Hungary's influence into southern Italy.
The third son of Charles I of Hungary and his wife, Elizabeth of Poland, born on March 5, 1326, is named for his father's uncle, Louis, Bishop of Toulouse, canonized in 1317.
The first-born son of Louis's parents, Charles, died before Louis's birth.
Louis became his father' heir in 1329 after the death of his brother Ladislaus.
He has had a liberal education by the standards of his age and learned French, German and Latin.
He showed a special interest in history and astrology.
A cleric from Wrocław, Nicholas, had taught him the basic principles of Christian faith.
However, Louis's religious zeal is due to his mother's influence In a royal charter, Louis will remember that in his childhood, a knight of the royal court, Peter Poháros, often carried him on his shoulders.
His two tutors, Nicholas Drugeth and Nicholas Knesich, had saved the lives of both Louis and his younger brother, Andrew, when Felician Záh attempted to assassinate the royal family in Visegrád on April 17, 1330.
He was only nine when he stamped a treaty of alliance between his father and John of Bohemia.
A year later, Louis had accompanied his father in invading Austria.
On March 1, 1338, John of Bohemia's son and heir, Charles, Margrave of Moravia, signed a new treaty with Charles I of Hungary and Louis in Visegrád.
According to the treaty, Charles of Moravia acknowledges the right of Charles I's sons to succeed their maternal uncle, Casimir III of Poland, if Casimir dies without a male issue.
Louis also pledges that he will marry the margrave's three-year-old daughter, Margaret.
Casimir III's first wife, Aldona of Lithuania, dies on May 26, 1339.
Two leading Polish noblemen—Zbigniew, chancellor of Cracow, and Spycimir Leliwita—had persuaded Casimir, who had not fathered a son, to make his sister, Elizabeth, and her offspring his heirs.
Historian Paul W. Knoll writes that Casimir preferred his sister's family to his own daughters or a member of a cadet branch of the Piast dynasty, because he wanted assure the king of Hungary's firm against the Teutonic Knights.
Louis's father and uncle sign a treaty in Visegrád in July whereby Casimir III makes Louis his heir if he dies without a son.
In exchange, Charles I pledges that Louis will reoccupy Pomerania and other Polish lands lost to the Teutonic Order without Polish funds and will only employ Poles in the royal administration in Poland.
Louis receives the title of Duke of Transylvania from his father in 1339, but he does not administer the province.
According to a royal charter from the same year, Louis's bride, Margaret of Bohemia, lived in the Hungarian royal court.
Louis's separate ducal court is first mentioned in a royal charter of 1340.
