The brutality always struck me not only as cruel, but stupid.
Even if they were successful in their conquests, how did the leadership expect to hold them for long, if the subjugated people all hated their guts?
There is an old joke about the Japanese invasion of China, which an American reporter was covering. On a PA system in a Chinese village, daily announcements were made of casualty figures on the fighting front. Over a three-day period, they went: 10,000 Chinese - 3,000 Japanese; 20,000 Chinese - 2,000 Japanese; 30,000 Chinese - 1,000 Japanese. The reporter noticed an old Chinese man in a tea house smiling at the announcements. "Why are you smiling?" asked the reporter. "Your forces are taking a terrible beating." The old man sipped his tea contentedly, and said, "Pretty soon... no more Japanese."