 Caliph Umar successfully tackled the alliance by putting pressure tactics on Byzantine front and deceptive tactics on Persian front and engaging Yazdegerd III into negotiations, this rendered the alliance and a would be decisive plan abortive.The Byzantine forces were decisively defeated in Battle of Yarmouk fought in August 636, Persian army was defeated in Battle of Qadisiyyah three months later in November 636.Muslim victory pertinently ended Byzantine rule south of Anatolia, and Jerusalem fall in April 637 after a prolonged siege, Umar personally came to receive the key to the city by the Greek Orthodox patriarch, Sophronius, and invited to offer Muslims prays at the Church of the Holy Sepulchre.