There is an English version in the second half.
この記事は、あくまでも私が学習した時の備忘録です。
前回の記事はこちら
白村江の戦いと国防の歴史①
白村江の戦いと国防の歴史②
白村江の戦いと国防の歴史③
日本の庇護を離れた高句麗は、自立自存のために自らの軍事力を高めなければならないということで、徹底した国防の強化を図りました。
兵に訓練を施し、どこから攻められても屈しない強力な国家を築き上げました。
その頃、周辺諸国を片っ端から攻めていった随王朝が誕生しました。
そして随はとうとう、その征服の矛先を高句麗に向けてきました。
ところが、高句麗も軍事大国として鍛え上げられてきたので強かったのです。
これで、随は徹底的にやられてしまいました。
国力で言えば、高句麗と随ではまったく違うにもかかわらず、何度戦いを挑んでも、大軍を送り込んでも、高句麗が勝利しました。
この度重なる戦闘が原因で随は国力が疲弊し、ついに随は倒れてしまいました。
その後に興ったのが唐でした。
唐は、随がなぜ滅んだのかを当然研究しました。
そして、その原因が高句麗であることを突き止めました。
そこで唐は「お家芸」の「遠交近攻」でいくことにしたのです。
遠交近攻とは、遠くの国と友好関係を結び、近くの国を攻めるという戦略です。
唐から地理的に見た時、高句麗の向こうにある国は、百済と新羅でした。
百済は倭国（日本）と仲が良いので手出しができませんでした。
そこで、以前から日本とあまり友好的な関係が築けていない新羅と手を組むことにしたのです。
History of the Battle of Hakusukinoe and National Defense ④
Click here to read the previous article.
History of the Battle of Hakusukinoe and National Defense (1)
History of the Battle of Hakusukinoe and National Defense (2)
History of the Battle of Hakusukinoe and National Defense (3)
After leaving the protection of Japan, Koguryo had to enhance its own military power for self-reliance and self-survival, and it thoroughly strengthened its national defense.
It trained its soldiers and built a powerful nation that would not yield no matter where it was attacked.
At that time, the Sui Dynasty was born, which attacked neighboring countries from one side to the other.
The Sui dynasty finally turned its conquests toward Goguryeo.
However, Goguryeo was also strong because it had been trained as a military power.
This was enough to thoroughly defeat Zui.
In terms of national strength, Goguryeo and Sui were completely different, but no matter how many times they challenged each other or how many large armies they sent, Goguryeo was victorious.
Due to these repeated battles, Sui’s national power became exhausted, and finally Sui collapsed.
The Tang Dynasty arose afterwards.
The Tang naturally studied the reason why Sui was destroyed.
And they found out that the cause was Goguryeo.
Therefore, the Tang Dynasty decided to use the “specialty” of “distant contact and close attack”.
The strategy of “distant contact and close attack” was to establish friendly relations with distant countries and to attack nearby countries.
Geographically viewed from the Tang Dynasty, the countries beyond Goguryeo were Baekje and Silla.
Baekje could not be meddled with because it was on good terms with Japan.
Therefore, they decided to join hands with Silla, which had not had very friendly relations with Japan before.