纵览中国历史，但凡一个大一统王朝初定，总是希望四夷宾服。明朝也不例外，朱元璋即位之初就派使臣下国书到日本，表达了两个意思：一是希望他们来朝贡，二是责令他们解决扰明倭寇问题。结果，国书送达后，日本不仅没来朝贡，反而砍了使者的脑袋。泱泱天朝大国被小小岛国羞辱，朱元璋恼羞成怒，扬言出兵，要征服日本。

针对朱元璋的开战威胁，日本摄政王怀良亲王针锋相对，以绵里藏针回信。这封信不卑不亢，同时给予“天朝”面子却暗藏强硬态度，小小日本，为何敢杀大明使臣？

这首先与两场历史巨变有关。一是在南宋灭亡前期；二是在抗击蒙古侵略后的经验教训中。在南宋时期，一直以来中国是日本心目中的榜样。而在抗击蒙古时期，由于连续失利，最终导致船队遭遇台风摧毁，这些经历让日本增强了抵御中国入侵的信心，对中国崇拜感也随之减弱。

虽然百年后汉人复国成功，但继起的明王朝在当时的观念中已失去了正统的地位。对于朱元璋来说，他鄙视、日本并非他所尊敬和追求的大同文明。但对于怀良亲王及其政府来说，他们认为自己有资格继承中华文明。

战争一触即发，但面对朱元璋步步紧逼的情况下，当政者还是寸步不让。除了上述两个理由，还有什么更能撑得住呢？追寻深层次，我们发现：Japanese leaders’ "strategic" vision and even the basis for Japan's confidence in resisting China. They believe that China as a force, against external pressure is extremely limited, has never had a record of conquering sea island nations, how can they claim to have experience in naval warfare? So this king who controls half of Japan thinks that while their country's strength is not yet strong enough to fight with China, but they dare not do what the Mongols did. The threat from Zhu Yuanzhang was just empty words.

As expected by Japan, despite repeated disrespect from Japan, Zhu Yuanzhang still only talked big but dared not take action. It is unknown whether he feared Japanese "god wind", or dreaded repeating the mistakes of the Mongols, or simply veiled his power and waited for an opportunity.

Later on, Zhu Yuanzhang left behind a Dan Shu Tie Guan certificate explicitly stating that Japan was a "non-conquered nation". It seemed like he found face-saving through Japanese response - since Japan called me "Heavenly Court", themselves as "vassals", I will also be broad-minded and no longer pursue matters regarding the killing of envoys.

Zhu Yuanzhang's decision appeared grandiose but was actually out of necessity — I won't attack you if you don't provoke me. During the Ming dynasty period, although China held significant superiority over tiny belligerent Japan — both in terms of national power and military might — from two countries' confrontation spirit it presented an equilibrium state.

Thus concludes our analysis into why Zhu Yuanzhang did not launch military campaigns against Japan despite being repeatedly humiliated by them: historical context intertwined with strategic thinking led to this outcome.