In the first chapter, The Soldier Saint Sun Tzu said: "Soldiers, the great affairs of the country, the way of survival, the land of death and life, must not be unaware!" He also said, "Know your enemy and never lose a battle." Zhuge Liang's way of using soldiers followed the principles of Sun Tzu's Art of War. Zhuge Liang did not take Wei Yan's suggestion to attack Chang'an with a surprise army, not because Zhuge Liang was too cautious and careful, but because with the strength of the Shu state, he could not implement Wei Yan's suggestion.
Among the three kingdoms, the Shu state was the weakest, with few soldiers, no generals, no wealth, no people, a small land area, limited resources, and only more than 900,000 people in the shu han country.
However, to support more than 100,000 troops, but also to support more than 40,000 officials, coupled with repeated troops in the Northern Expedition, the country has been exhausted, and the common people have long been overwhelmed.
However, in order to compete with Cao Wei for orthodoxy, but also to resolve internal crises, Zhuge Liang also had to insist on the Northern Expedition.
With Zhuge Liang's wisdom, would he not be able to see the general trend of the world? Don't you know that using the weak Shu state to fight the powerful Wei state is equivalent to hitting a stone with an egg?
Fighting with soldiers is not a game, and once you fail, it is difficult to recover.
When Cao Cao was so powerful, didn't the defeat at the Battle of Chibi also deprive him of the ability to attack Jiangnan?
Cao Cao couldn't bear the fiasco, let alone the weak Shu state.
If the weak side wants to fight against the superior enemy, it cannot opportunistically hold a lucky victory mentality. The front line of the Shu Wei battle was in Hanzhong and Ganliang Prefectures, where both countries had a large number of troops.
If Zhuge Liang had taken Wei Yan's advice and attacked Chang'an in a combined attack, he would inevitably face several dangers.
First, if Wei Yan was unable to complete the task or failed, it would certainly cause heavy losses to the Shu army and shake the morale of the Shu army.
Second, the Shu state had limited troops, and if it went deep into the enemy's territory but could not conquer Chang'an, it would be likely to be surrounded and suppressed by the heavy troops of the State of Wei. Moreover, there were only a few valley roads in Hanzhong leading to Ganliang Prefecture, and if the Wei army cut off the Retreat Route of the Shu Army, the Shu Army would surely die without a place to die.
Third, even if the Shu army can occupy the two prefectures of Ganliang, it still needs to divide its troops to defend each city. And the strong Wei army will definitely fight back. At that time, the Shu army will fall into a situation where its forces are scattered, unable to concentrate its superior forces against the Wei army, and unable to maintain the land pool it has already occupied.
Third, if an army wants to maintain its combat effectiveness, it needs sufficient grain and grass material support. However, the Shu Road was difficult and the transportation of materials was extremely inconvenient. Therefore, if the Shu army drove straight into the hinterland of the Wei state, it would be difficult to obtain timely and sufficient logistical supplies due to the lengthening of the battle line. If the enemy adopts the strategy of fortifying the wall and clearing the wilderness, the Shu army will fall into a desperate situation.
Fourth, the local factions within the Shu Kingdom and the foreigners are not without conflicts of interest, but because the foreigners are too strong, the local factions have lost their right to speak. Zhuge Liang was a representative figure of the foreign faction and had a decisive influence in the Shu dynasty. Therefore, Zhuge Liang could neither fail nor bear the consequences of failure. Just think, just because of the misuse of ma Mo and the loss of the street kiosk, Zhuge Liang had to kill Ma Mo first, and then he would have to show himself on the table, and if he suffered a big defeat, he would have to do it!
To sum up: Because the internal and external situation facing the Shu state was quite severe, Zhuge Liang was forced to adopt a conservative tactic of fighting steadily and steadily step by step during the Northern Expedition, and to advance inch by inch. Zhuge Liang could not fail, and the Shu kingdom could not withstand the blow of failure! Therefore, zhuge liang, in the situation that he could not make a quick decision, let alone settle a battle, could only reject Wei Yan's seemingly clever sneak attack plan and try to win by chance!