The Guards were the first of the guard style guilds which were created with the purpose to protect the community from PKs. Though the name we know today is The Guards, their original name was The Guards of Dawn which lasted about a month before the guild was restructured. Founded by Lost Boy and Alrein around April 6th, 1998, the guild was formed on the principles of democracy. They chose to elect each of their ranks and leadership, creating a cooperative guild. The guild was developed with the same idea of protecting players from the rise of PKs like Tibia's first guild, but with the added belief that they should subject lawfulness on all of Tibia. To facilitate this end, they needed to become strong so they recruited as many players as they could. This trait would make this Tibia's first large guild.
As you might expect despite the good intentions, the community grew to hate this guild for interfering in their conflicts. Inviting so many players resulted in many who were less then honorable in upholding the ideals of the guild which further shrank their good will in the community. The guild found itself often fighting the community more then against the PKs they were designed to fight. Dark guilds like PoD, the Assassins, and others were rumored to fight openly with the guild though I couldn't find any specific instances of conflict mentioned, only remarks from guild pages and forum posts.
Beyond fighting PKs the guild arranged quests for its members in its earlier day, though this only appears to have happened a few times. What these quests were or how involved they might be is unknown. One of the interesting caveats of the guild was that they kept reasonably good records of events so much of the early timeline of Tibia was only known because they maintained records which survived. Most guild websites were preoccupied with recording news of themselves, like a new member joining or a guild meeting, so it is nice to see actual news from Tibia which is rare.
The guild codex has 11 tenets which are detailed below:
"(1) First, all members should be aware that they are part of a large guild, and their actions and words represent not only themselves but the guild as well. Therefore, everyone should try to be friendly and, above all, not blatant. So be careful with statements that address the treatment of fellow players.
(2) Members should at all times conduct themselves in accordance with the code of honor, and always display the following virtues: honesty, compassion, justice, honor and humanity.
(3) The guild council directs and directs the guild.
(4) Members may not attack another player. However, they are allowed to defend themselves and come to the aid of any other player who has been attacked without provocation.
(5) If members encounter or are attacked by a known P-Killer, or witness a P-Killer attacking a player, they should eliminate that player on the spot.
(6) When guild members encounter two players fighting each other, they should try to stop the fight unless both parties have agreed to it. If the fight cannot be prevented, it is advisable to help the victim. Incidents of this kind must be reported to the guild officials.
(7) Members may not attack members of other guilds unless the guards are at war with that guild.
(8) Members should strive to help players who are in need or weak.
(9) Members are not allowed to disclose secret guild information.
(10) Membership in other guilds is prohibited.
(11) The guild council reserves the right to punish violations of the code of honor with the appropriate penalty."
The membership of the guild was made up of several different layers with the High Council making up the leadership of the guild. These players were the Guild Elder, Treasurer, Diplomat, and Council President, plus others who were deemed worthy. Alrein, the Guild Elder, was one of the founders and had a permanent spot in the council. The treasure was an elected official who ran the guilds financing, collecting taxes from the guild and maintaining the guild hall. Most early guilds had a Diplomat position to help negotiate with other guilds and the Guards was no different. This was also an elected passion. The Council President was the speaker for the guild, who was the voice of the entire council, making decisions, and voicing the councils will to the other members.
Outside of the council was the Archmage, Lord of the Elements, Paladin Master, and Berseker titles which were given to the most powerful mages, druids, paladins, knights of the guild. They lead the other members of their vocation but had no tasks themselves. They were considered honored and had some sway with the council.
The bulk of the guild made up the normal members who were grouped and labeled as their procession. They had very little say in important decisions but were able to recommend potential new members unlike the lowest class of the guild which was the Novice. The Novice was those who had just joined the guild and had no say in any maters. They could procession to membership status once they reached level 10 and had been in the guild for a bit.