As such, he was expected to pay the highest share of the annual tribute to be given to the Abyssinian Emperor. Emir Laday Usman subsequently marched to Dakkar and seized power in 1471. However, Usman did not dismiss the Sultan from office, but instead gave him a ceremonial position while retaining the real power for himself. Adal now came under the leadership of a powerful Emir who governed from the palace of a nominal Sultan. Adalite armies under the leadership of rulers such as Sabr ad-Din II, Mansur ad-Din, Jamal ad-Din II, Shams ad-Din and general Mahfuz subsequently continued the struggle against Abyssinian expansionism. Emir Mahfuz, who would fight with successive emperors, caused the death of Emperor Na'od in 1508, but he was in turn killed by the forces of Emperor Dawit II (Lebna Dengel) in 1517. After the death of Mahfuz, a civil war started for the office of Highest Emir of Adal. Five Emirs came to power in only two years. But at last, a matured and powerful leader called Garad Abuun Addus (Garad Abogne) assumed power. When Garad Abogne was in power he was defeated and killed by Sultan Abu Bakr ibn Muhammad, and In 1554, under his initiative, Harar became the capital of Adal. This time not only the young Emirs revolted, but the whole country of Adal rose against Sultan Abu Bakr, because Garad Abogne was loved by the people of the sultanate. Many people went to join the force of a young imam called Ahmad ibn Ibrahim al-Ghazi, who claimed revenge for Garad Abogne. Al-Ghazi assumed power in Adal in 1527, however he did not remove the Sultan, but instead left him in his nominal office. Yet, when Abu Bakr waged war on him, Ahmad ibn Ibrahim killed Abu Bakr, and replaced him with his brother Umar Din. They fought under a combination of three banners used by Ahmad al-Ghazi  In the 16th century, Adal organised an effective army led by Imam Ahmad ibn Ibrahim al-Ghazi that invaded the Abyssinian empire. This campaign is historically known as the Conquest of Abyssinia or "Futuh al Habash". During the war, Ahmed pioneered the use of cannons supplied by the Ottoman Empire, which were deployed against Solomonic forces and their Portuguese allies led by Cristóvão da Gama.