It has been more than 400 years since signal flags were used for communication on ships. The advantage of banner communication is very simple. Therefore, even today when modern communication technology is quite developed, this simple communication mode is still preserved and becomes an important way of short-distance communication. In sign communication, signal signs can be used alone or in combination to express different meanings. Usually hanging a flag indicates the most urgent, important or commonly used content. For example, the A-flag is hoisted, which means "There are divers under my boat, please stay away from my boat slowly"; Hang the O-flag, which means "someone falls into the water"; Hanging the W flag means "my ship needs medical assistance" and so on.
At the end of Qin Dynasty, Chen Sheng and Guangwu planned an uprising under the tyranny of II. In order to contact the masses, a note with the words "Great Chu Xing, Chen" was put in the fish's stomach. When the masses saw it, they believed that Bobby Chen would be expensive because of the tradition of telepathy between man and nature, so they secretly fell for it.
According to legend, in the Yuan Dynasty, the Han people were miserable under the rule of the Yuan people, and Zhu Yuanzhang fought against the Yuan. However, the Yuan army was tightly controlled and the rebels could not deliver the message. So, Liu Bowen presented a plan of giving cakes to each other in the Mid-Autumn Festival, and put a note inside, which read "Kill Tartars on August 15th" as a signal of the uprising.
The Revolution of 1911 overthrew the Manchu dynasty. However, the fruits of the revolutionary victory were stolen by Yuan Shikai. After Yuan Shikai ascended the throne of the great president, he attempted to restore the monarchy and become emperor himself. Some people who catered to him, after intensive preparations, finally realized the "imperial system." So it was promulgated that the world was changed to yuan, and like the emperors of previous dynasties, the year number was formulated and it was decided to use "Hong Xian". He ordered all government documents, newspapers and periodicals all over the country to use the words "the first year of Hongxian" on the year number, or they would be convicted as appropriate. Shi Shen, the host of Shanghai Shen Bao, is very opposed to the restoration of monarchy. He was not convinced, but he had to reluctantly agree. After careful consideration, the king of newspapers had an idea. He asked the compositor to find a word similar to the word "xian" and put it behind the word "hong" to prevaricate. As a result, the words "the first year of flood" suddenly appeared in the next day's Shenbao. That day's "Shen Bao" suddenly became a hot commodity, because it spoke the voice of the people.
In ancient times, letters were easily damaged due to the fatigue of ships and cars. The ancients put letters in boxes and carved them into the shape of fish, which was both beautiful and convenient to carry.
"Guests from afar leave me a pair of carp" in Gulefu's Journey to the Great Wall means that guests from afar give me a carp-shaped wooden box with letters in it. "Tiger cooks carp, and there is a book in it" means: Tell the boy and servant to open the wooden box, and there is a long letter written in plain silk.