His mother was Devletşah Hatun, the daughter of Süleyman Şah of Germiyanids and Mutahhara Abide Hatun bint-i Sultan Veled bin Mawlānā Jalal al-Din Muhammad Rumi. İsa worked as a sanjak governor in Antalya and fought in the Battle of Ankara in 1402 with his father. In 1403, after learning about his father"s death in captivity, began to struggle for the vacant throne against his brothers Mehmet Çelebi, Musa Çelebi, and Süleyman Çelebi.
The name Çelebi is an honorific title meaning gentleman. See pre-1934 Turkish naming conventions. İsa was one of the sons of Beyazid I, the Ottoman sultan.
The Ottoman army was defeated, Beyazid I was captured by Timurlane, and İsa escaped to west Anatolia.
He fought against Musa to gain control of Bursa, the Anatolian capital of the empire. But the European territory, Rumeli, was under the control of Süleyman and the east part of Anatolian territory was under the control of Mehmet (the future Mehmet I).
But following this refusal, he was defeated by Mehmet in the Battle of Ulubat in 1405. In this battle, he also lost his vizier Timurtaş, who was an experienced statesman.
He escaped to Rumeli over Byzantine territories.
He met with Süleyman, who supported his cause in Anatolia. With fresh troops provided by Süleyman, he returned to Anatolia and tried to recapture Bursa. Although he failed, allying himself with the Anatolian beyliks, which his father Beyazıt I had captured but which had regained independence after Beyazıt"s defeat at the Battle of Ankara, he continued to fight against Mehmet.
However, after a series of defeats and the betrayal of his allies, İsa gave up the war for the throne.
According to historian Joseph von Hammer, after losing the struggle, İsa went into hiding. According to other sources, however, he was spotted in a public bath (Turkish: hamam) in Eskişehir and killed by Mehmet"s partisans in 1406.
After his death, the interregnum continued till 1413. In 1413, Mehmet became the sole ruler of the empire as Mehmet I after defeating Musa.
