Early life

Yang Hong was from Wuyang County (武阳), Qianwei Commandery (犍为), which is located within present-day Pengshan, Sichuan. When Liu Zhang was the governor of the Yi Province, he served successively in several commanderies. After Liu Bei successfully conquered Yi province, Li Yan recommended him as an Officer of Merit (功曹). Later, Li Yan wished to relocate the Administrator's headquarters, however Yang Hong firmly opposed this decision and in the end his opinion was ignored. Following this, he resigned from his position as an Officer of Merit. However, Li Yan still recommended Yang Hong to the Prefectural capital as an official.

Service under Liu Bei

Afterward, when Liu Bei battling Xiahou Yuan at Hanzhong, he sends requests for reinforcement to be sent. At this time, Zhuge Liang was in charge of the approvisionnement and asked Yang Hong's opinion about this. Yang Hong told him: Zhuge Liang agreed with Yang Hong's opinion.

At the same moment, the Administrator of Shu Commandery (蜀郡太守), Fa Zheng was helping Liu Bei in the north. Zhuge Liang sends a memorial to have Yang Hong take the vacant position, he quickly adapted and the many problems were soon all resolved therefore he was given the formal appointment. Soon he was relocated to another office in Yi province.

After Liu Bei proclaimed himself emperor, he launched a campaign against Wu but was unsuccessful and retreated to Yongan. At this time, the Administrator of Hanjia Huang Yuan (黄元) had a bad relationship with Zhuge Liang and fearing that after Liu Bei's death would have problems led a rebellion in his commandery, he burned down the city of Linqiong. During this Zhuge Liang had left to examine the condition of Liu Bei therefore Chengdu was weak and badly defended, Huang Yuan was all the more excessive and fearless in his attitude. Yang Hong at once informed Liu Chan to dispatch their own personal troops along with the Generals Chen Hu (陈曶) and Zheng Chuo (郑绰) to suppress Huang Yuan's rebellion.

Everyone was afraid that if Huang Yuan failed to conquer Chengdu, he would try to occupy Hanzhong from Yuexi. However, Yang Hong said: And indeed, Yang Hong's prediction was true and Huang Yuan was taken alive. After this, he was enfeoffed as the "Marquis Within the Passes" (关内侯), resumed his occupation as Administrator of Shu Commandery and given the rank of General of Loyalty and Integrity (越骑校尉) and later became Lieutenant Cavalry of Yueqi (越骑校尉).

Service under Liu Shan

In 227, Zhuge Liang moved to the north and make his headquarters in Hanzhong, wanted to employ Zhang Yi in his office as his Chief Clerk (长史) and asked Yang Hong's opinion about this. Yang Hong told him: When young, Yang Hong and Zhang Yi were close friend however when Zhang Yi was in exile in Wu and Yang Hong temporarily took charge of his commandery. He didn't give special treatment to his son Zhang Yu, who was a minor official when he committed a small offence. When Zhang Yi came back to Shu, he heard about this and was resentful of Yang Hong, from this moment their relation deteriorated.

Later, when Yang Hong saw that Zhuge Liang was raising troops. He personally visited Zhang Yi and told him what he advised Zhuge Liang about him. Zhang Yi answered that Zhuge Liang already appointed him and that he couldn't prevail this. People were thinking that Yang Hong's intention was to be Chief Clerk at the place of Zhang Yi or that knowing Zhang Yi was resentful of him, Yang Hong didn't want for him to occupy a critical position and manage important matters. However when in position, Zhang Yi had conflict with the Colonel (校尉) Chen Shu (岑述) until their relation reached hatred and anger. Zhuge Liang knew about this and send a letter to Zhang Yi where he reprimand him for not putting the interest of the State before his personal relation. Because of this event, the people understood that Yang Hong was truthful in his statement.

Anecdote

When Yang Hong was young, he didn't enjoy scholarship, but he was a faithful and altruistic man. He was concerned about the wellbeing of others as if they were his own family and was known to treat his stepmother with utmost filial piety. He died while serving in office in 228. At first, Yang Hong served under Li Yan but due to personal opinions, he retired however while Li Yan was still serving as Administrator of Qianwei, Yang Hong had been already relocated as Administrator of Shu Commandery. At this time, he was helped by He Zhi, who served under him as a personal Aide Officer. He Zhi was talented, smart, made numerous accomplishments and was soon promoted to the role of Prefect. Several years later, he was promoted again to be the Administrator of Guanghan. At the same time, Yang Hong was still serving as the Administrator of Shu Commandery. Because of this, all the people in the west admired Zhuge Liang for his ability to thoroughly employ the men of great talent.

生平

杨洪在刘璋任益州牧时曾到多个郡任职，刘备夺益州后，犍为太守李严任命杨洪为功曹。后来因李严意欲搬迁犍为郡的治所，不顾杨洪极力反对，杨洪于是辞任功曹。李严于是推荐杨洪当蜀部从事。刘备争夺汉中时大力支持出兵夺取汉中以保持益州安定，得到诸葛亮赏识而表杨洪领蜀郡太守，任内尽力办公，因此被升为蜀郡太守。不久转任益州治中从事。

刘备称帝后，便出兵征讨东吴，发动夷陵之战，但最终被击败，退到永安。

汉嘉太守黄元听闻刘备患病，而自己向来和诸葛亮不和，害怕一旦刘备逝世，诸葛亮当权后会遭到报复，于是趁成都空虚叛乱，纵火烧临邛，杨洪于是派将军陈曶和郑绰讨伐黄元，当时众人都认为黄元战败后会逃到南中固守，但杨洪认为黄元不会这样，必会沿江东下逃走，派陈曶等在南安峡口阻截，最后果然生擒黄元。建兴元年（223年），赐爵关内侯，再次被任命为蜀郡太守、忠节将军，后来担任越骑校尉，继续治理蜀郡。

杨洪不好学问，但他忠心事朝，对公事如同家事般紧张，建兴六年（228年）在任内逝世。

三国演义

在65回，杨洪随刘璋投降。在80回提及杨洪是治中，91回提及孔明任命杨洪为尚书。但三国志只提及杨洪做过治中，没有说他做过尚书。