Yuan Zhen suppressed Zhang Hu due to political intrigue and power struggle within the Tang Dynasty. Yuan Zhen, a prominent official, sought to consolidate his power by eliminating potential threats, including Zhang Hu, who was seen as a rival.

Yuan Zhen's suppression of Zhang Hu was driven by several factors. Firstly, Zhang Hu held significant influence and power within the government, which posed a direct threat to Yuan Zhen's authority. According to historical records, Zhang Hu was a close associate of Emperor Xuanzong, which gave him considerable leverage and influence over the imperial court. This made Zhang Hu a prime target for Yuan Zhen, who aimed to diminish his influence to strengthen his own position.

Secondly, there was a growing rivalry between Yuan Zhen and Zhang Hu, which was evident in their political and administrative decisions. Yuan Zhen, as the Chancellor, was responsible for overseeing the civil service and implementing policies, while Zhang Hu, as the Minister of Revenue, had control over the financial resources of the state. Their differing approaches and interests often led to conflicts, making Zhang Hu a liability for Yuan Zhen's political ambitions.

Historical data supports the notion that Yuan Zhen's suppression of Zhang Hu was a strategic move to eliminate a potential rival. For instance, the "Tangshu" (Book of the Tang) records that Yuan Zhen accused Zhang Hu of corruption and mismanagement, which led to Zhang Hu's demotion and eventual exile. This move not only weakened Zhang Hu's influence but also served as a warning to other officials who might challenge Yuan Zhen's authority.

Furthermore, the suppression of Zhang Hu was part of a broader pattern of political intrigue during the Tang Dynasty. The period was marked by frequent power struggles and coups, as various factions vied for control of the imperial court. Yuan Zhen's suppression of Zhang Hu was a clear example of how political rivals were eliminated to maintain stability and consolidate power.

In conclusion, Yuan Zhen suppressed Zhang Hu due to political intrigue and power struggle within the Tang Dynasty. Zhang Hu's significant influence, growing rivalry with Yuan Zhen, and the broader context of political intrigue all contributed to his downfall. Historical records, such as the "Tangshu," provide evidence of Yuan Zhen's strategic move to eliminate a potential rival and strengthen his own position within the government.