Why was the Ming so bad at war? And how did they last that long?
Of the major Imperial Chinese dynasties like Han, Tang, Song, Yuan, etc. the Ming seemed to have been the most blessed when it came to their enemies. While other dynasties had to face very potent nomadic empires (Xiongnu, Khitan Liao, Jurchen Jin, Mongol themselves), strong state opponents (Gorguyeo, Abbasid, Western powers like the British and the French), and major peasants rebellions (the Yellow Turban, the Red Turban, the Taiping), the Ming faced none of the above. The Nomads they faced were weak (the Yuan being reduced to the rump state of North Yuan), their state opponents weren't that strong when compared to others (the Japanese in the Imjin war, while potent, was not as overpowering to them as the later British/French), and they didn't face major peasant rebellion until Li Zhicheng.
And yet, they got their butts spanked, bad. Their emperor was captured at Tumu, their army was bogged down in Korea, their entire coast had to be evacuated as they could not deal with piracy. The Song dynasty, widely considered to be a disgrace to China, fought off the Liao, the Jin, and the Mongols for a hundred year; the Yuan, a foreign empire in a majority Chinese country, fought off environmental calamities and peasant uprising for a solid twenty years before collapsing; the Qing survived 70 years since the beginning of the Opium war through multiple defeats and humiliation. And there the Ming was, collapsing in a mere fifty years.
So, why were the Ming so bad?