In terms of the objective you defined in the question, the Shu army had a reasonable chance of success. Liu Bei's army held two significant advantages:

• Superior infantry: the Shu army consisted of battle hardened, professional veterans who were better versed in field combat than Wu soldiers, especially in mountainous regions. The strength of the Wu military was in their navy. On the ground, Wu forces were largely ineffectual against relatively fewer Wei defenders than their Shu counterparts.

• Home ground: The backbone of the Shu forces were from the Jing province. This applied to both his officer corps, and also to the rank and file. Not only was morale high in the fight to recapture their homes from the Wu invaders, Shu's diplomats (also Jing natives) were quite successful in inciting the regional minorities into rebellion against Wu.

In terms of overall strategic situation, Shu had the additional advantage that Wei's armies were poised for an invasion of the South. In fact, Wu's forces were facing a war on two fronts, leading the following exchange soon after the battle:

劉備聞魏軍大出、書與遜云「賊今已在江陵、吾將復東、將軍謂其能然不？」遜答曰「但恐軍新破、創痍未復、始求通親、且當自補、未暇窮兵耳。若不惟算、欲復以傾覆之餘、遠送以來者、無所逃命。」

Liu Bei, hearing of the Wei invasion, wrote Lu Xun to say, "I heard the enemy has reached Jiangling. I'm thinking of returning to the East too. What do you think?"

Lu Xun replied, "I'm afraid your army was just defeated, and haven't recovered from wounds and illnesses yet. It is time to sue for peace and recuperate, instead of pursuing jingoism. If you don't listen, and insist on on attacking after a defeat, the soldiers you send will have no place to run."

_{-- 《晉·張勃·吳錄》}

Throughout the Wei invasion, Lu Xun stayed in position blocking Liu Bei's invasion path. By the time Wei forces lifted the siege due to rampaging disease, Jiangling was on the verge of surrendering, and relief forces scrapped together from elsewhere were repulsed every time. Lu Xun's inaction demonstrates how potentially formidable Liu Bei's surviving forces still were, at least in the minds of Wu's leaders.

Given the tactical and strategic advantages in Shu's favour, Liu Bei's invasion had at least some chance of success for retaking western Jing. On the other hand, pushing further east would have been an entirely different question; the extra distance significantly shifts logistical and terrain advantages in Wu's favour. If Liu Bei intended the Shu invasion to conquer all of Jing or even Wu itself, then you could say the invasion was doomed. The Shu navy's depleted state would by itself rule out conquering beyond Jiangling.

Note that Liu Bei's invasion was not "hasty" by any means. The Shu province was captured in 214. Kuan Yu was defeated and killed in 219. It took until 222 before Liu Bei launched his invasion. By this point Liu had administered the Yi province for 8 years. For reference, Liu began his conquest of Yi a mere 4 years after taking control of Jing.

In terms of the objective you defined in the question, the Shu army had a reasonable chance of success. Liu Bei's army held two significant advantages:

• Superior infantry: the Shu army consisted of battle hardened, professional veterans who were better versed in field combat than Wu soldiers, especially in mountainous regions. The strength of the Wu military was in their navy. On the ground, Wu forces were largely ineffectual against relatively fewer Wei defenders than their Shu counterparts.

• Home ground: The backbone of the Shu forces were from the Jing province. This applied to both his officer corps, and also to the rank and file. Not only was morale high in the fight to recapture their homes from the Wu invaders, Shu's diplomats (also Jing natives) were quite successful in inciting the regional minorities into rebellion against Wu.

In terms of overall strategic situation, Shu had the additional advantage that Wei's armies were poised for an invasion of the South. In fact, Wu's forces were facing a war on two fronts, leading the following exchange soon after the battle:

劉備聞魏軍大出、書與遜云「賊今已在江陵、吾將復東、將軍謂其能然不？」遜答曰「但恐軍新破、創痍未復、始求通親、且當自補、未暇窮兵耳。若不惟算、欲復以傾覆之餘、遠送以來者、無所逃命。」

Liu Bei, hearing of the Wei invasion, wrote Lu Xun to say, "I heard the enemy has reached Jiangling. I'm thinking of returning to the East too. What do you think?"

Lu Xun replied, "I'm afraid your army was just defeated, and haven't recovered from wounds and illnesses yet. It is time to sue for peace and recuperate, instead of pursuing jingoism. If you don't listen, and insist on on attacking after a defeat, the soldiers you send will have no place to run."

_{-- 《晉·張勃·吳錄》}

Throughout the Wei invasion, Lu Xun stayed in position blocking Liu Bei's invasion path. By the time Wei forces lifted the siege due to rampaging disease, Jiangling was on the verge of surrendering, and relief forces scrapped together from elsewhere were repulsed every time. Lu Xun's inaction demonstrates how potentially formidable Liu Bei's surviving forces still were, at least in the minds of Wu's leaders.

Given the tactical and strategic advantages in Shu's favour, Liu Bei's invasion had at least some chance of success for retaking western Jing. On the other hand, pushing further east would have been an entirely different question; the extra distance significantly shifts logistical and terrain advantages in Wu's favour. If Liu Bei intended the Shu invasion to conquer all of Jing or even Wu itself, then you could say the invasion was doomed. The Shu navy's depleted state would by itself rule out conquering beyond Jiangling.

That said, forcing a negotiated settlement seem like the more likely plan on Liu Bei's part.

Note also that Liu Bei's invasion was not "hasty" by any means. The Shu province was captured in 214. Kuan Yu was defeated and killed in 219. It took until 221 before Liu Bei launched his invasion. By this point Liu had administered the Yi province for 7 years. For reference, Liu began his conquest of Yi a mere 4 years after taking control of Jing.