He was known to the Crusaders as Saphadin (derived from his laqab or honorific title Sayf ad-Din, meaning "Sword of Faith"), a name by which he is still known in the Western world.

He first achieved distinction as an officer in Nur ad-Din Zengi's army during his uncle Shirkuh's third and final campaign in Egypt (1168–1169); following Nur ad-Din's death in 1174, Al-Adil governed Egypt on behalf of his brother Saladin and mobilized that country's vast resources in support of his brother's campaigns in Syria and his war against the Crusaders (1175–1183).

[7] In the disputes which followed al-Adil often found himself in the position of honest broker between al-Afdal Ali and his brother al-Aziz Uthman, trying to keep the peace.

[7] Eventually however al-Adil concluded that al-Afdal Ali was simply unfit to rule, and he supported al-Aziz Uthman to become Sultan in his place, forcing his brother into exile.

Al-Afdal Ali was invited back to Egypt to act as regent to al-Aziz Uthman's twelve-year-old successor, al-Mansur Mohammed.

Fleeing to Cairo, al-Afdal sued for peace on any terms he could get from al-Adil; stripped of Egypt he was promised the cities of Samosata and Mayyafaraqin.

The resulting drought and famine were serious threats, but by a range of measures including sending his soldiers out to work the land, al-Adil ensured continued social and political stability as well as economic recovery.

Of particular importance was the marriage of his daughter Dayfa Khatun to Saladin's son Az-Zahir Ghazi of Aleppo in 1212, which marked the end of the rivalry between the two branches of the family.

The campaigns in Palestine did not bring him any notable success however, and in August 1218 (Jumada 1 615) he received the shocking news that a second Crusader force had landed in Egypt and were attacking Damietta.

Elsewhere, Saladin's descendants retained Aleppo, and the family of Al-Adil's other brother Nur ad-Din Shahanshah held Baalbek and Hama.

Damascus became the main focus of rivalry between different branches of the family, changing hands a number of times before Ayyubid rule came to an end.