Charles I died on 16 July 1342.
Five days later, Csanád Telegdi, Archbishop of Esztergom, crowned Louis king with the Holy Crown of Hungary in Székesfehérvár.
Although Louis had attained the age of majority, his mother Elizabeth "acted as a sort of co-regent" for decades, because she exerted a powerful influence on him.
Louis inherited a rich treasury from his father, who had strengthened royal authority and ruled without holding Diets during the last decades of his reign.

Louis introduced a new system of land grants, excluding the grantee's brothers and other kinsmen from the donation in contrast with customary law: such estates escheated to the Crown if the grantee's last male descendants died.
On the other hand, Louis often "promoted a daughter to a son", that is authorized a daughter to inherit her father's estates, although customary law prescribed that the landed property of a deceased nobleman who had no sons was to be inherited by his kinsmen.
Louis often granted this privilege to the wives of his favorites.
Louis also frequently authorized landowners to apply capital punishment in their estates, limiting the authority of the magistrates of the counties.

William Drugeth, an influential advisor of Louis's late father, died in September 1342.
He bequeathed his landed property to his brother, Nicholas, but Louis confiscated those estates.
In late autumn, Louis dismissed his father's Voivode of Transylvania, Thomas Szécsényi, although Szécsényi's wife was a distant cousin of the queen mother.
Louis especially favored the Lackfis: eight members of the family held high offices during his reign.
Andrew Lackfi was the commander of the royal army during the first war of Louis's reign.
In late 1342 or early 1343, he invaded Serbia and restored the Banate of Macsó, which had been lost during his father's reign.

Robert the Wise, King of Naples, died on 20 January 1343.
In his testament, he declared his granddaughter, Joanna I, his sole heir, excluding Louis's younger brother, Andrew, Joanna's husband, from becoming co-ruler.
Louis and his mother regarded this as an infringement of a previous agreement between the late kings of Naples and Hungary.
He visited his bride's father, Charles of Moravia, in Prague to persuade him to intervene on Andrew's behalf with Charles's former tutor, Pope Clement VI, the overlord of the Kingdom of Naples.
Louis also sent envoys to his Neapolitan relatives and the high officials of the kingdom, urging them to promote his brother's interests.
Their mother, Elizabeth, left for Naples in the summer, taking with her almost the whole royal treasure, including more than 6,628 kilograms (14,612 lb) of silver and 5,150 kilograms (11,350 lb) of gold.
During her seven-month-long stay in Italy, she was only able to persuade her daughter-in-law and the pope to promise that Andrew would be crowned as Joanna's husband.

According to the nearly contemporaneous chronicle of John of Küküllő, Louis launched his first campaign against a group of Transylvanian Saxons, who had refused to pay taxes, and forced them to yield in the summer of 1344.
During his stay in Transylvania, Nicholas Alexander – who was the son of Basarab, the ruling prince of Wallachia – swore loyalty to Louis on his father's behalf in Brassó (now Brașov in Romania); thus the suzerainty of the Hungarian monarchs over Wallachia was, at least outwardly, restored.

Louis joined a crusade against the pagan Lithuanians in December 1344.
The crusaders – including John of Bohemia, Charles of Moravia, Peter of Bourbon, and William of Hainaut and Holland –  laid siege to Vilnius.
However, a Lithuanian invasion of the lands of the Teutonic Knights forced them to lift the siege.
Louis returned to Hungary in late February 1345.
He dispatched Andrew Lackfi to invade the lands of the Golden Horde in retaliation for the Tatars' earlier plundering raids against Transylvania and the Szepesség (now Spiš in Slovakia).
Lackfi and his army of mainly Székely warriors inflicted a defeat on a large Tatar army.
Thereafter the Golden Horde's control of the lands between t
Charles I died on 16 July 1342. Five days later, Csanád Telegdi, Archbishop of Esztergom, crowned Louis king with the Holy Crown of Hungary in Székesfehérvár. Although Louis had attained the age of majority, his mother Elizabeth "acted as a sort of co-regent" for decades, because she exerted a powerful influence on him. Louis inherited a rich treasury from his father, who had strengthened royal authority and ruled without holding Diets during the last decades of his reign.
Louis introduced a new system of land grants, excluding the grantee's brothers and other kinsmen from the donation in contrast with customary law: such estates escheated to the Crown if the grantee's last male descendants died. On the other hand, Louis often "promoted a daughter to a son", that is authorized a daughter to inherit her father's estates, although customary law prescribed that the landed property of a deceased nobleman who had no sons was to be inherited by his kinsmen. Louis often granted this privilege to the wives of his favorites. Louis also frequently authorized landowners to apply capital punishment in their estates, limiting the authority of the magistrates of the counties.
William Drugeth, an influential advisor of Louis's late father, died in September 1342. He bequeathed his landed property to his brother, Nicholas, but Louis confiscated those estates. In late autumn, Louis dismissed his father's Voivode of Transylvania, Thomas Szécsényi, although Szécsényi's wife was a distant cousin of the queen mother. Louis especially favored the Lackfis: eight members of the family held high offices during his reign. Andrew Lackfi was the commander of the royal army during the first war of Louis's reign. In late 1342 or early 1343, he invaded Serbia and restored the Banate of Macsó, which had been lost during his father's reign.
Robert the Wise, King of Naples, died on 20 January 1343. In his testament, he declared his granddaughter, Joanna I, his sole heir, excluding Louis's younger brother, Andrew, Joanna's husband, from becoming co-ruler. Louis and his mother regarded this as an infringement of a previous agreement between the late kings of Naples and Hungary. He visited his bride's father, Charles of Moravia, in Prague to persuade him to intervene on Andrew's behalf with Charles's former tutor, Pope Clement VI, the overlord of the Kingdom of Naples. Louis also sent envoys to his Neapolitan relatives and the high officials of the kingdom, urging them to promote his brother's interests. Their mother, Elizabeth, left for Naples in the summer, taking with her almost the whole royal treasure, including more than 6,628 kilograms (14,612 lb) of silver and 5,150 kilograms (11,350 lb) of gold. During her seven-month-long stay in Italy, she was only able to persuade her daughter-in-law and the pope to promise that Andrew would be crowned as Joanna's husband.
According to the nearly contemporaneous chronicle of John of Küküllő, Louis launched his first campaign against a group of Transylvanian Saxons, who had refused to pay taxes, and forced them to yield in the summer of 1344. During his stay in Transylvania, Nicholas Alexander – who was the son of Basarab, the ruling prince of Wallachia – swore loyalty to Louis on his father's behalf in Brassó (now Brașov in Romania); thus the suzerainty of the Hungarian monarchs over Wallachia was, at least outwardly, restored.
Louis joined a crusade against the pagan Lithuanians in December 1344. The crusaders – including John of Bohemia, Charles of Moravia, Peter of Bourbon, and William of Hainaut and Holland –  laid siege to Vilnius. However, a Lithuanian invasion of the lands of the Teutonic Knights forced them to lift the siege. Louis returned to Hungary in late February 1345. He dispatched Andrew Lackfi to invade the lands of the Golden Horde in retaliation for the Tatars' earlier plundering raids against Transylvania and the Szepesség (now Spiš in Slovakia). Lackfi and his army of mainly Székely warriors inflicted a defeat on a large Tatar army. Thereafter the Golden Horde's control of the lands between t
Louis I of Hungary