What is the cause of An Lushan's rebellion? What's his slogan?

The slogan of An Lushan's rebellion is relatively simple, mainly through the imperial edict against Yang. As for the reasons for An Lushan's rebellion, there are subjective factors, class contradictions, objective advantages and so on, which are worth discussing. I can analyze three main reasons.

First of all, An Lushan is not really loyal to Li Tang. He is an ambitious man. Although An Lushan rebelled under the banner of punishing the traitor Yang, this so-called banner was actually the same as Judy's slogan of "Battle of Jing Nan" in the Ming Dynasty. To put it bluntly, this is just an excuse for his "famous start". The real intention is to fight for the sovereignty of the dynasty. Before launching the war, An Lushan deliberately provoked the war with the surrounding ethnic minorities, so that the imperial court could send more troops to his jurisdiction. This is actually a means for An Lushan to expand its forces and prepare for future battles. In addition, it can be seen from An Lushan's various performances after he rose up, that An Lushan rose up just to be emperor, which was the most important reason for his rebellion.

Second, although the crusade against Yang is just an excuse, there are indeed many contradictions between An Lushan and Yang. Yang rose rapidly under Yang Guifei's favor until she became prime minister, but her own qualities and talents did not match those of the prime minister. She clashed with An Lushan for power and profit, and even slandered Li Longji many times to defeat An Lushan. Therefore, it can also be said that the contradiction between An Lushan and Yang was the direct cause of the Anshi Rebellion, and An Lushan's rebellion was undoubtedly aimed at eliminating Yang.

Third, its powerful strength and corruption in the Tang Dynasty provided favorable objective conditions for An Lushan to rebel. Li Longji made great efforts in his early years, and gradually degenerated since the late Kaiyuan period, indulging in debauchery and extravagance. On the one hand, the adultery between Li and Yang leads to political corruption, speech occlusion and increasingly fierce class contradictions. At the local level, land annexation is becoming more and more serious, resulting in many civilians losing their fields and becoming refugees. On the other hand, the border areas are getting stronger and stronger, while the quantity and quality of the Central Army are very weak.

When An Lushan started, he was the special envoy sent by our army to the three northeastern regions, with a total strength of nearly 200,000 people. He was a tough minority soldier with strong fighting capacity. These are the emboldened and favorable factors of An Lushan's rebellion.