What were the prophet Muhammed's greatest achievements?

Alphonse de Lamartine says on this point, Never has a man proposed for himself, voluntarily or involuntarily, a goal more sublime, since this goal was beyond measure: undermine the superstitions placed between the creature and the Creator, give back God to man and man to God, reinstate the rational and saintly idea of divinity in the midst of this prevailing chaos of material and disfigured gods of idolatry. Never has a man accomplished in such short time such an immense and long lasting revolution in the world, since less than two centuries after his prediction, Islam, preaching and armed, ruled over three Arabias and conquered to God's unity Persia, the Khorasan of Transoxania, Western India, Syria, Egypt, Abyssinia, and all the known continent of Northern Africa, many islands of the Mediterranean, Spain, and part of Gaul. Edward Gibbon adds, The Mahometans have uniformly withstood the temptation of reducing the object of their faith and devotion to a level with the senses and imagination of man. 'I believe in One God and Mahomet the Apostle of God' is the simple and invariable profession of Islam. The intellectual image of the Deity has never been degraded by any visible idol; the honors of the prophet have never transgressed the measure of human virtue, and his living precepts have restrained the gratitude of his disciples within the bounds of reason and religion. Similarly, after the renowned Mahatma Gandhi (d. 1948) found himself in prison with the Prophet's biography, he was able to identify the secret behind the Prophet ﷺ overcoming insurmountable odds and reaching such stations of global success. He says, I wanted to know the best of the life of one who holds today an undisputed sway over the hearts of millions of mankind… I became more than ever convinced that it was not the sword that won a place for Islam in those days in the scheme of life. It was the rigid simplicity, the utter self-effacement of the Prophet, the scrupulous regard for pledges, his intense devotion to his friends and followers, his intrepidity, his fearlessness, his absolute trust in God and in his own mission. These and not the sword carried everything before them and surmounted every obstacle. Bosworth Smith (d. 1908), a reverend schoolmaster and author, writes, By a fortune absolutely unique in history, Mohammed is a threefold founder of a nation, of an empire, and of a religion… Head of the State as well as the Church; he was Caesar and Pope in one; but he was Pope without the Pope's pretensions, and Caesar without the legions of Caesar, without a standing army, without a bodyguard, without a police force, without a fixed revenue. If ever a man ruled by a right divine, it was Muhammad, for he had all the powers without their supports. He cared not for the dressings of power. The simplicity of his private life was in keeping with his public life.