Upon the invitation of several Hungarian lords, who turned against
Andrew III of Hungary, the young Charles and his accompaniment landed at
Split in
Dalmatia in August 1300. They arrived with only two galleys, a carrier ship and 150 horses, which reflected the very low number of his escort, consisting of Italian and French knights. Among them, only Philip Drugeth took a significant role in the subsequent unification war against the
oligarchic domains and the governance of the realm. By the arrival of Charles, the young pretender's political situation had drastically worsened, because Andrew III reconciled with the most powerful oligarchs, including
Matthew Csák and
Henry Kőszegi. Even after Andrew's death and the extinction of the
Árpád dynasty in January 1301, the overwhelming majority of the barons supported the claim of
Wenceslaus of Přemyslid, Charles' rival. The struggle for the Hungarian throne during the so-called Interregnum characterized the next decade. There is no information about any of Drugeth's activity in this period, who has reached adulthood during these years. According to Serbian historian Đura Hardi, Drugeth became acquainted with his new homeland, the temper and customs of the provincial lords against whom he was soon going to fight, after Charles became the lawful and only King of Hungary after his third coronation in 1310. , when he was appointed castellan of
Szepes Castle (today in
Spišské Podhradie, Slovakia) in 1315 The burghers of
Kassa (now Košice in
Slovakia) assassinated the oligarch
Amadeus Aba in September 1311. After that Charles I was committed to eradicating the
Abas' oligarchic rule. However, Amadeus' sons rebelled against the king. Following a series of military skirmishes in the spring of 1312, the young Philip Drugeth participated in the siege of
Sáros Castle (today Šariš in Slovakia) in late April or early May 1312, when Charles' army seized the fort from the Aba-ally
Zólyom (Balassa) kinship. During the siege, Drugeth distinguished himself and had received two "deathly wounds". Thereafter Charles waged war against Matthew Csák in order to "recovering of occupied royal property" in early 1313, capturing
Nagyszombat. Drugeth participated in this campaign. By that time, he was one of the chief commanders of the royal army. It is possible, however, the royal charter of 1317, which narrates the merits of Philip, refers to the failed military expedition against Matthew Csák in September 1311. , which was captured by Philip Drugeth in 1317 Charles' aforementioned charter also refers to another clash between Philip Drugeth and Matthew Csák in the area of "Scepus". Accordingly, the oligarch invaded the land in order to loot and destroy the royal landholdings, but Drugeth won a "glorious victory" and successfully repulsed his army. Historian
Gyula Kristó argued Matthew's attack occurred at the turn of 1314 and 1315, and identified with the place with the region of
Szepesség (or Zips, today Spiš, Slovakia). In fact, Matthew Csák, who plundered the region, was narrowly defeated by the royal army. During the decisive battle, Drugeth was almost captured, his arm was severely wounded and his life was saved by one of his
familiares Nicholas Tekele. In contrast, historian
Pál Engel identified "Scepus" with the town of
Szepsi (today Moldava nad Bodvou, Slovakia) and dated the clash to the first half of 1317. Philip Drugeth was first styled as
ispán of
Szepes County and castellan of its
namesake castle in March 1315 (his initial main residence). Pál Engel argued Charles resided in the Szepesség region in late 1314 and dismissed his former loyal barons, the brothers Kakas and Henry Tarkői from their positions in Szepes and
Sáros counties, respectively. Following that Charles appointed Philip Drugeth and
Mikcs Ákos as the new heads of the aforementioned counties. In contrast, Kristó considered Charles arrived to the region to strengthen his royalist faction in Northeast Hungary, and there is no record of any military activities in the region in that year. Kristó argued Drugeth fought against Matthew Csák, when he was already
ispán. Drugeth held both offices until his death. With this appointment, he became one of the barons of the realm, granting his first landholdings and "office fiefs" (or
honors). He is considered founder and first member of the Drugeth de Homonna family, which had integrated into the Hungarian nobility. , which was captured by Philip Drugeth in 1317 The influential
Borsa clan, in alliance with
Peter, son of Petenye rebelled against Charles I in the second half of 1316. Peter – initially a loyal soldier of the king – rose to prominence in Northeast Hungary, exploiting that political vacuum, which emerged following the dissolution of the Abas' dominion. In response, Charles appointed Philip Drugeth as
ispán of
Abaúj County (or Újvár) in late 1316, replacing
John Aba, who could not hinder Peter's rapid expansion in the region. In contemporary documents, Drugeth first appeared as head of the county in March 1317. Charles immediately responded to the unfavorable developments and launched a multi-faceted war against
James Borsa and his allies in early 1317. The king initiated a royal campaign first against Peter, the weakest member of the anti-Charles coalition. Philip Drugeth and Mikcs Ákos simultaneously led troops against Peter's forts in
Ung County in the first months of 1317. Around March, Drugeth captured
Gönc, then his army marched in front of
Regéc Castle, also joined by
Ladislaus Baksa's auxiliary troops due to a threatening leaf by Drugeth. Regéc was besieged and seized in April. In the same time, Mikcs Ákos crushed Peter's power in
Zemplén County, capturing the castles
Barkó (Brekov), Borostyán and
Bodrogszög (Klin nad Bodrogom) within few weeks. Peter's last stronghold
Jeszenő (Jasenov) was taken by Philip Drugeth in the last days of April or early May 1317 (according to Engel, Matthew Csák's surprise attack against Szepsi also occurred around that time). Attila Zsoldos proposes Drugeth took the title
ispán of Zemplén County after Peter's defeat, holding the dignity until 1320, potentially in parallel with his local rival, Ladislaus Baksa. Drugeth was present in the royal camp, when Charles invaded Matthew Csák's domains and captured
Visegrád and
Komárom (now Komárno in Slovakia) in the autumn of 1317. The sons of the late Amadeus Aba rebelled against the king again in late 1317, because their political and social status has declined against the emerging new nobility in the region, including Philip Drugeth and Mikcs Ákos, who were sent to crush their rebellion. Drugeth captured their forts at
Boldogkő and their possessions in Sáros County. Philip Drugeth participated in the military expedition against Serbian king
Stefan Milutin in the summer of 1319, during which Charles retook
Belgrade and restored the
Banate of Macsó. Thereafter,
Dózsa Debreceni and Drugeth eliminated the power of the sons of the late oligarch
Stephen Ákos in
Borsod and
Gömör counties since the autumn of 1319. Drugeth besieged and captured their castle at Dédes. The war against the Ákos sons continued until the next year. Around August, Dózsa and Drugeth seized another forts in
Heves, Gömör and
Nógrád counties. Drugeth was present at the sieges of
Sirok and
Fülek (today Fiľakovo, Slovakia). Drugeth was made
ispán of Gömör and
Torna counties in 1320, holding both offices until his death. It is plausible that he also became
ispán of Borsod and
Heves counties around that time. After Matthew Csák died in March 1321, the royal army invaded the deceased lord's province, which soon disintegrated because most of his former castellans yielded without resistance. Drugeth's troops joined the royal army in late April. Drugeth and his several
familiares – including
Nicholas Perényi and
Blaise Fonyi – participated in the sieges of the castles of
Tapolcsány and
Trencsén (now Topoľčany and Trenčín in Slovakia, respectively). ==Formation of the Drugeth Province==