The history of spies is so long that its origins in both the East and the West date back 4,000 years.
While the history of espionage in the West began in earnest in the 16th or 17th century, in China it began in earnest more than 2,000 years earlier, during the Warring States Period.
In the case of spies in our country, it started around the time of the Common Era and reached its peak in the 7th century, during the Three Kingdoms period.
Even if we only consider the peak period, it is nearly a thousand years ahead of the West.
However, until now, we have only reproduced the records of the great generals who led wars to victory, and we have never dealt with the history of the spies who changed the rise and fall of a nation and even the international situation behind them.
This was partly due to the secrecy of spy activities, but also because the Confucian ideology that valued legitimacy was strengthened, the secret activities of spies were looked down upon.

This book sheds new light on spies, who were previously considered supporting characters in history.
We look at familiar figures from the perspective of spies, such as Kim Yu-sin, a master of espionage; Eulji Mundeok, who became a spy himself and went behind enemy lines; and Prince Hodong and Princess Nakrang, the first married couple of spies in our history.
Additionally, the ingenious and diverse espionage techniques of ancient spies are displayed in an exciting way, such as obtaining information about the enemy general's affair and leading the war to victory, and assassinating the enemy general by hiding a dagger in a dish.

Then, King Jangsu 'recruits' spies.
Of course, the recruitment at this time was carried out under strict security.
The monk Dorim was selected as a spy.
Dorim applied and asked for a chance to repay the country's favor.
King Jangsu, who had confirmed that Dorim was a man of strong patriotism, gave Dorim the basic information about Baekje that he had obtained so far, and after discussing a plan to infiltrate Baekje, he made it seem like he had committed a crime and fled.
Dorim chose Baduk as a means of approaching King Gaero, which was likely due to prior knowledge that King Gaero liked Baduk.
Dorim also reached the level of a national master in the game of Baduk.
If so, it is highly probable that King Jangsu listed baduk as one of the qualifications when recruiting spies.
Dorim, who successfully infiltrated Baekje, captured the heart of King Gaero through baduk.
And using this, he successfully persuaded King Gaero to undertake large-scale civil engineering projects through his skillful speaking skills, building magnificent and splendid palaces, castles, and pavilions, and even having the tomb of the former king renovated in a grand manner.
As a result, Baekje "was faced with a crisis more serious than the Yellow River crisis, with its granaries empty and its people in poverty."
Dorim, judging that the time was ripe, secretly escaped Baekje and returned to his country to report the situation to King Jangsu.
King Jangsu was very pleased that things were going according to his plan and immediately sent his army to attack Baekje.
King Garo was defeated, humiliated, tied up in ropes, and had his head cut off.

---p.35