During his search for the Avatar, Zhao, a Commander at the time, traveled to the Pohuai Stronghold to request use of the Yuyan Archers in capturing Aang. At first, Colonel Shinu denied his request, calling Zhao's goal nothing but a vanity project, but when the commander was promoted to admiral status, Zhao commanded Shinu to release the archers to his cause. The archers quickly tracked down Aang while he was searching for a cure to a fever Sokka and Katara had contracted. After capturing him, they detained Aang in the Pohuai Stronghold prison, where Zhao taunted him and proclaimed victory before the fortress defenders. However, this victory was short-lived as a mysterious masked bandit known as the Blue Spirit infiltrated the fortress and rescued Aang from Zhao's capture. However, the masked man was knocked unconscious by an archer in the process. Aang managed to escape with the Blue Spirit, who he later discovered to be PrinceZuko, leaving Zhao infuriated.
The fortress was a structure made up of multiple stone walls surrounding a large pagoda tower at the center of the base. The walls were coated with iron to protect it from earthbenders. The building housed its own prisons and was a major materiel depot for the Fire Nation Army. This massive metal structure was built by the Fire Nation military as a troop and supply hub where soldiers and firebenders trained before they were deployed into battle. Supplies were moved from the stronghold over thousands of miles of rail lines to the Fire Nation Army assembling at the outskirts of Ba Sing Se.
Some of the firebenders from the stronghold garrison had no face plates.