How did Syria get war torn?

The Arab Spring movement brought hopes for reform throughout most of the Middle East and North Africa. It brought hope for one of the Middle East's most repressed people in Syria.
Protests for reform began in Deraa on March 15th 2011. Unsurprisingly they were met with repression and brutality. Some elements of the Syrian Army joined the protestors and fighting grew into a full civil war.
The Syrian government under Bashar al Assad was supported by Russia, Iran and Iran's Lebanese ally, Hezbollah. The opposition was composed of pro-democracy, pro-Sunni Islamic forces (supported by the Saudi and Gulf states), Kurds (supported by the US) and extreme Islamic forces like Al-Qaida.
Many of the battles have taken place in populated areas. Heavy artillery, bombing from the air and use of chemical weapons took a terrible toll on ordinary men, women and children. By 2015 almost 11 million people had been forced to leave their homes. Almost 4 million had become refugees, mostly in Jordan, Turkey, Lebanon and Iraq.
By 2014 one opposition group had become most powerful, ISIS or Islamic State. This group supported the most extreme form of Sunni Islam. It received support from Gulf states. It spent as much time fighting other opposition groups as the Syrian army. It drew fighters from all over the world. It occupied a large part of Syria and Iraq.
In 2015 Russia upped its involvement by increasing its level of aerial bombing on opposition forces. The US supported Kurdish forces to fight against IS. In 2017 President Trump withdrew the US from the operation. In 2018 Turkey created a buffer area along the northern Syria border to protect itself from Kurdish forces. In 2019 this was accepted by Russia, the Syrian Government and Iran.
Today Syria is a mess. The Government controls most of the country. The Kurds control an area in the North. Turkey controls an area along the border. IS (Islamic State) is largely destroyed. Millions of Syrians are displaced throughout their country and outside it.