In the first week of the First Zeon War, millions died as a result of indiscriminate nuclear, biological, and chemical attacks on Federation and civilian targets. In a horrific operation codenamed Operation British, Zeon forces initiated a colony drop that would ultimately lead to the destruction of Sydney, Australia.
All that remains of Sydney is a massive crater, with the colony fragment that destroyed it still standing in the middle of the impact. Water is already flowing into the crater, forming the Gulf of Sydney.
To this day, the Sydney Crater will forever remain an enduring symbol of the horrors of the Zeon Wars.