The Barmakid family, which had faithfully served the previous four Abbasid caliphs as viziers, came under scrutiny in 803. The Barmakid viziers had reformed, consolidated, and rebuilt the bureaucracy and infrastructure of the Umayyads, and indeed had improved on those foundations to make one of history's most efficient, powerful, and for the time, extremely tolerant states. The Barmakids, whose religious tolerance had been often criticized by conservative Muslims, had not been Muslims for long; indeed, they had been Buddhistss until not long before the arrival of the Arabs in Persia, and then had become Zoroastrianss, and then converted to Islam. Viewed by many as mercenary, and for their Persian blood viewed as foreigners, they had attracted a great deal of unpopularity among the elites and citizens of the Caliphate.
In 803, a scandalous relationship was uncovered between the Barmakid vizier and an Abbasid princess. Harun's mother, al-Khayzuran, was outraged for the insult to her family. She also, for reasons of her sex, had been marginalized during the period of Harun's regency, and asked Harun to act. The Caliph, who had been annerved by the power of the Barmakid family in politics and wished to improve the strength of his office, had the leading members of the Barmakid family executed. They did not return to public service.
When Harun was only eighteen years old he showed such courage and skill as a soldier that his father, who was then caliph, allowed him to lead an army against the enemies of the Muslims; and he won many great victories.
He later commanded an army of ninety-five thousand Arabs and Persians, sent by his father to invade the Eastern Roman Empire, which was then ruled by the Empress Irene. After defeating Irene's famous general, Nicetas, Harun marched his army to Chrysopolis (now Scutari) on the Asiatic coast, opposite Constantinople. He encamped on the heights, in full view of the Roman capital.
The Empress saw that the city would certainly by taken by the Muslims. She therefore sent ambassadors to Harun to arrange terms; but he sternly refused to agree to anything except immediate surrender.
It is reported that then one of the ambassadors said, "The Empress has heard much of your ability as a general. Though you are her enemy, she admires you as a soldier."
These flattering words were pleasing to Harun. He walked to and fro in front of his tent and then spoke again to the ambassadors.
"Tell the Empress," he said, "that I will spare Constantinople if she will pay me seventy thousand pieces of gold as a yearly tribute. If the tribute is regularly paid Constantinople shall not be harmed by any Muslim force."
The Empress agreed to these terms. She paid the first year's tribute; and soon the great Muslim army set out on its homeward march.
Harun became caliph when he was almost twenty-one years old. He began his reign by appointing very able ministers, who carried on the work of the government so well that they greatly improved the condition of the people.
Harun built a palace in Baghdad, far grander and more beautiful than that of any caliph before him. He established his court there and lived in great splendor, attended by hundreds of courtiers and slaves.
He was very anxious that his people should be treated justly by the officers of the government; and he was determined to find out whether any had reason to complain. So he sometimes disguised himself at night and went about through the streets and bazaars, listening to the talk of those whom he met and asking them questions. In this way he learned whether the people were contented and happy, or not.
Harun al-Rashid gave great encouragement to learning. He was a scholar and poet himself and whenever he heard of learned men in his own kingdom, or in neighboring countries, he invited them to his court and treated them with respect.
The name of Harun, therefore, became known throughout the world. It is said that a correspondence took place between him and Charlemagne and that Harun sent the great emperor a present of a clock and an elephant.
The tribute of gold that the Empress Irene agreed to pay Harun was sent regularly for many years. It was always received at Baghdad with great ceremony. The day on which it arrived was made a holiday. The Roman soldiers who came with it entered the gates in procession. Muslim troops also took part in the parade.
When the gold had been delivered at the palace, the Roman soldiers were hospitably entertained, and were escorted to the main gate of the city when they set out on their journey back to Constantinople.
Then he dictated a letter to Nicephorus, in which he said:
Nicephorus was now forced to agree to pay the tribute. Scarcely, however, had the caliph reached his palace in Baghdad when the emperor again refused to pay.
Harun, consequently, advanced into the Roman province of Phrygia, in Asia Minor, with an army of 15,000 men. Nicepherus marched against him with 125,000 men. In the battle which followed the emperor was wounded, and 40,000 of his men were killed.
After this defeat Nicephorus again promised payment of the tribute, but again failed to keep his promise. Harun now vowed that he would kill the emperor if he should ever lay hands upon him. But as he was getting ready to march once more into the Roman provinces a revolt broke out in one of the cities of his own kingdom; and while on his way to suppress it the great caliph died of an illness which had long given him trouble.