Personally, I like Ma Chao. I like his character. I dislike how people tend to be less harsh on people who were defeated by Cao Cao at his peak, but somehow gather the aggression to say Ma Chao was worthless, or nearly worthless.
He was born from a Qiang mother, so his duty to the Qiang, whom his father had been protecting and friendly with, is a key role in his actions later in his life.
When Ma Teng fell out with Han Sui, requesting a station in the capitol, Ma Chao was given command of Ma Teng's troops. He was young, but not without experience. With his father, he marched against Guo Yuan and Gao Gan, where he and Pang De (his subordinate at the time) defeated the two opponents.
When Ma Chao and Han Sui forged their alliance and marched against Cao Cao, Xiahou Yuan and Xu Huang had already been going about the area putting down rebellions. As many of the rebels had assistance from minority tribes, the Qiang could be, understandably, in danger. Because of this, raising a rebellion against Cao Cao while Zhong Yao (a governor who the border generals didn't trust, anyways) seemed like a good idea. Inlcuding his duty to the Qiang, his rebellion was necessary.
The campaign wasn't entirely unsuccessful, as many of the overlooking summaries I've read here have implied. His first assault was only unsuccessful because the enemy would not come out of their defenses. After this, when the enemy tried to cross the river, minor successes were had since they were able to keep the enemy at bay.
The Record of Cao Man wrote:His Excellency was preparing to cross the Yellow River and the main force had crossed ahead of him, when Chao and his men suddenly arrived, but His Excellency remained seated on his chair and did not rise. Zhang He and his men saw that the situation was urgent and joined together to lead His Excellency into the boat. The river water was flowing rapidly, the ferry traveling four or five li, and Chao and his men rode in pursuit, firing at them such that the arrows came down like rain. All of the generals saw the army was defeated and were not aware that His Excellency was in the boat, and all of them were very afraid, but upon seeing him their grief turned to jubilation and some of them shed tears. His Excellency smiled broadly, saying, ‘Today we were almost stranded here merely on account of a few bandits!’
Cao Cao's SGZ wrote:His Excellency went north of Tong pass to ferry across but did not do so and Chao hurriedly went towards his boat to attack. The Colonel Ding Fei for this reason released oxen and horses to bait the rebels, who became disordered and seized the oxen and horses, and His Excellency was thereupon able to cross, using the path of the river as a walled corridor and going south.
It was Ma Chao's force, and no other, that saw these crossings and countered them. Only through luck of timing and the season's cold air was Cao Cao able to build a makeshift wall to prevent the effectiveness of Ma Chao's cavalry from being felt.
Beyond simple notice of strategic placement, Ma Chao was also one who favored more graceful methods of assault. To quote:
Tales of Duke Shanyang wrote: Formerly, when Lord Cao’s army was at Puban, and getting ready to cross over the river to the west, Ma Chao said to Han Sui, “We should counter their troops north of the Wei river. In no more than 20 days, the supplies from east of the River would be exhausted and they would certainly retreat.” Han Sui said, “We should order our men to cross the river too, and attack them midstream—wouldn’t that be even better?” Thus Chao’s strategy was not employed. When Lord Cao heard of this, he said, “If the Ma kid does not die, I know not where I’d be buried.”
Even though his military feats were impressive, he also could realize when he couldn't find victory, and sought to cede land to Cao Cao in exchange for some of his children as hostages. This is when Cao Cao began to ruin the alliances west of the Pass.
After the initial battle, Xiahou Yuan was his main opponent. His counter attacks that came after his defeat at Tong Pass weren't without rewards.
Xiahou Yuan's SGZ wrote:Ma Chao surrounded the Inspector of LiangZhou Wei Kang at Ji. Xiahou Yuan went to rescue Wei Kang but did not arrive in time, hence Wei Kang was defeated. When Xiahou Yuan was still 200 li away from Ji, Ma Chao came out to fight in battle. Xiahou Yuan could not prevail. The Di rebelled and so Xiahou Yuan lead his army to return.
Surely, taking a commandery and so soon afterwards defeating one of Wei's best generals is not a feat to scoff at. After this victory, he was only flushed out of the city by conspirators from within, who tricked him into leaving to fight when former followers of Wei Kang attacked. This shows two things: 1) Ma Chao was not too foolish as to realize when it is best to stay behind safe walls, as he wasn't going to meet the retaliatory army initially, and 2) Ma Chao never had a solid following to support him and his military decisions.
From Tong Pass to the cities he took back from Wei, he never had a unified army; all of them looking for their own gain, or many seeking to surrender to Wei. Indeed, when Ma Chao surrounded another Wei city, his soldiers refused to fight when Zhang He came to relieve the city, and Ma Chao was forced to retreat.
When he was with Zhang Lu, he was not given the necessary means to recapture what he had lost. Add on top of this the fact that officers under Zhang Lu were continuously plotting against him and ruining his efforts, you can't possibly blaim Ma Chao alone for his failures.
When he went to Liu Bei, he was accepted with open arms, and it was his reputation and previous feats that earned Liu Zhang's army's fear.
Ma Chao's SGZ wrote:Liu Bei sent some followers to welcome Ma Chao and the latter led his men to the side of the Cheng Du city. There was great fear within the city and Liu Zhang immediately surrendered, upon the arrival of Ma Chao’s troops.
Dian Lue wrote:When Liu Bei heard that Ma Chao was coming, he said gleefully, “I am going to get Yi province!” Thus he sent an envoy to greet Chao, and secretly supplied him with troops. When Chao arrived, Liu ordered him to garrison north of the city. Chengdu fell within ten days of Chao’s arrival.
After Han Zhong was taken, Ma Chao was appointed as its governor because of Liu Bei's view of his role. Quoting Liu Bei:
Ma Chao's SGZ wrote:You (Ma Chao) are in good esteem of the northerners and your valor is well-known there and they are willing to follow you to fight against the evil across thousands of miles. You are to integrate them into the Han culture and be fair in your task to reward the good and punish the wrongdoers.
Ma Chao died not two years after his appointment in Han Zhong. This didn't give him time to esteem himself in the battles to come with Zhuge Liang's Northern Campaigns or even the Nanman Campaign. Perhaps he could have been utilized during Yi Ling. But remember, his accomplishments were not slight when he was without a strategist and without unity. How much more impressive would his victories be when he would have had them?
