借这个标题问一下，根据英文维基百科的资料所述：
https://en.wikipedia.org/wiki/Wang_Jian_(Qin)
里面有一段：
The first Qin invasion initially appeared successful but ended up in a major
disaster when the 200,000 Qin army was annihilated by a combined attack of
500,000 Chu troops led by General Xiang Yan and another army under the direct
command of Lord Changping, at the Battle of Chengfu in the unfamiliar
territory of Huaiyang(modern-day northern Jiangsu and Anhui provinces).
意思是项燕跟昌平君联合的楚军，人数多达50万人。
这样的话跟秦军60万人相比，也差不了太多。
就算这50万人是有把军伕、军眷计算在内，但秦军内不是也可能有军伕军眷吗？？
这样楚军在兵力上应该没有与秦军差太多。而且该文下面又记载：
In 224 BC, Wang Jian began the second invasion of Chu. Chu's morale had
greatly increased after their success the previous year. The Chu forces were
content to wait and defend their territory.
意思是楚军在前一年击败李信所率的秦军后，士气得到很大提升。
这样看来楚军在兵力并不居劣势，且从前一年对秦军作战中得到经验、士气。
而且楚国腹地广大，如果采用像早先李牧对秦军那样的战术：
也就是以坚强防守消耗秦军、并且故意放弃一些据点、路线，诱使秦军孤军深入，
等到秦军完全进入楚军的陷阱中再发动反击。
这样楚军有机会反败为胜吗？史实上赵军利用这个战术也确实击败过秦军：
https://en.wikipedia.org/wiki/Battle_of_Fei_(233_BCE)
Li Mu felt that the Qin army's morale was high after its earlier victories,
so it would be unwise for Zhao to attack Qin then. He ordered his troops to
strengthen their fortifications and defences while waiting for an opportunity
to launch an counteroffensive.
Li Mu predicted that Huan Yi would retreat from Fei to save the camp, he
ordered his men to lay an ambush on Huan Yi's retreat route. Huan Yi's
retreating troops fell into the ambush. Qin sustained over 100,000 casualties
in the battle and its army was almost completely wiped out.
只是因为赵国腹地比较小，比较没有空间一直使用这种战术。但是从西元前236年邺之战
到西元前228年邯郸沦陷，赵军也支撑了8年之久：
https://zh.wikipedia.org/wiki/%E7%A7%A6%E6%BB%85%E8%B6%99%E4%B9%8B%E6%88%B0
而楚国领土广大，有足够战略纵深，应有能力执行这种战术。
而且楚军即使有数十万人，也不可能处处都设防，而使用这种机动灵活的方式来防守，
可集中兵力，解决处处设防兵力分散的问题。
那么楚军有可能击败入侵的秦军，至少保住半壁江山呢？？
还是其实楚军是做不到这种程度的战术，要楚军做到这样其实是高估楚军的战斗力？？
而且楚军阵营没有像是李牧这样的将领，所以楚军被秦军击败是必然的？？