Following Frollo's defeat and ultimate demise at Notre Dame, it appeared Ba Sing Se was at peace once again. William MacKay was now the newest member of the Avatar Gang. He immediately began a relationship with Toph Beifong.

While the rest of the Avatar Gang, also known as Team Avatar, left Ba Sing Se to fight new threats at other places around the world, William and Toph decided to settle down in Ba Sing Se for a while and William helped his cleric friends spread Roman Catholicism throughout the city and eventually, the whole Earth Kingdom.

When William was 19 and Toph was 15, he asked her to marry him. To some people's surprise, she said yes and they married in Notre Dame. While this happened, William also began spreading his own culture to the Earth Kingdom by teaching everyone about the cultures of Ireland, England, and of course, Scotland. These ideas spread even faster than his religion.

After the events at Notre Dame, the Earth King thanked William by offering him a large area of land out in the rural parts of the Earth Kingdom. Within 2 years, William eventually used the favor the Earth King had given him to start an autonomous kingdom in the northern part of the Earth Kingdom. Eventually, he convinced him to grant him an area so large that it could be its own country.

William had used his books to spread his ideas. The topic that gained the biggest following was the history and culture of Scotland. Eventually, tens of thousands of people followed him and in 103 AG, they all formed a new Scotland in the northern Earth Kingdom. It was autonomous, so even though it was still technically a part of the Earth Kingdom, it was self-governing. Once Notre Dame received enough donations, a few smaller cathedrals were built there, along with many small villages. The capital was named Edinburgh, in honor of the capital of the old-world Scotland.

Unfortunately, darkness came upon the Earth Kingdom once again. While Aang and other members of the Gang were busy fighting Water Tribe rebels and Fire Nation loyalists, another group appeared. This time, it was people that at one point had followed William. One man named Eash, was more fascinated by culture and history of England.

Since William never got to see the end of the war between them and Scotland, Eash assumed that victory could instantly be achieved if he were put in a position of great power. He and many of his friends began a countermovement against William. The movement unexpectedly grew, and since enough people agreed on it, in 106 AG, the Earth King granted them much territory and the "new" England covered the entire northwest portion of the Earth Kingdom. Its capital was obviously named London.

When England first formed, William was suspicious of their intentions, especially when for royalty purposes, Eash instantly adopted the name Edward I. This so happened to be the name of the king William Wallace and his army fought against.

Throughout the years the two kingdoms spent developing, William and Toph had seven children, two girls and five boys.

Toph named the girls Lin and Suyin. William named the boys William Jr after himself and William Wallace, Robert after Robert the Bruce, who was Wallace's closest ally, and Hamish, Campbell, and Stephen, all named after soldiers in Wallace's army, who were close friends with him and Wallace.

Toph had William Jr at 17 years old, Robert at 18, Lin at 20, Hamish at 21, Campbell at 22, Stephen at 25, and finally Suyin at 27.

In 116 AG, when William was 32 and Toph was 28, the newly formed and autonomous Republic City attempted to become a safe haven for all benders who wanted to come together to form a multicultural society. After a couple attacks on the city, the city council personally went to Toph, offering her the position of Chief of Police, claiming she was the only person they trusted to properly enforce the law and put an end to the violence.

The offer, which Toph eventually accepted, put a strain on her marriage to William. After many minor insults and major arguments, the two separated. They officially stayed married, but Toph moved to Republic City, taking the girls with her, while the boys stayed in Scotland with William.

When it formed, Scotland was locally divided by provinces, each represented by and named after newly formed clans. The new Clan MacKay, in charge of the MacKay province, was based in the middle of the country. In the middle of the province was Edinburgh.

Just off the south coast of England in Yue Bay, there is an island which was previously uninhabited. After discovering it, Aang settled there and built an air temple for him, Katara, and their future family. It is now referred to as Air Temple Island.

In the northwest portion of the world, west of England and north of the Fire Nation, there is a large island surrounded by four smaller islands. Before the genocide, the main island was inhabited by airbenders at the Western Air Temple. It was briefly used by the Gaang toward the end of the Hundred Year War while Aang practiced firebending.

A minority of William's followers began practicing Irish culture rather than Scottish. As a way to remain allies with William and prevent a civil war, the Irish moved to the island. It is now referred to everybody as Ireland. Also, Aang, being the last airbender until having children, permitted the Irish to move there, as long as they preserved the temple. They agreed and in 110 AG, Ireland was formed.

On the other side of the world was another island. On it was the Eastern Air Temple. Just like the Irish, another minority of William's followers grew. They practiced the lesser known Welsh culture. Once again, with Aang's permission, the Welsh moved to the island and preserved the temple. Wales was formed in 112 AG.

Eash, now known as Edward I, and nicknamed Longshanks by Scottish citizens who despised him, craved power based simply off of his knowledge of the old-world English history. He openly praised William the Conqueror, who led the Norman invasion of Anglo-Saxon England and often used him as reference to promote and enforce interventionist policies. Eventually, it reached a breaking point.

In April of 125 AG, the leader of Clan Ferguson, which shared a river border with England, passed away. Before dying, he made the mistake of not having any heir to his throne. Longshanks took this as a sign that he was meant to conquer Scotland one province at a time. One week later, England invaded the Ferguson province. Within two days, England captured it and thus began the War of Scottish Independence.