Guardian Units of the Nations

The Guardian Units of the Nations, also abbreviated as GUN or G.U.N., is an organization that appears in the Sonic series created by Yuji Naka. It is a worldwide military and law enforcement organization, affiliated with the President, armed with their expertise in warfare in order to protect humanity and maintain peace on the planet. Run by Commander Abraham Tower, G.U.N. seeks to protect the world from all sorts of threats, including Dr. Eggman, the Black Arms, or the Dark Gaia Creatures.

G.U.N. has vast resources, including an army of soldiers and peacekeepers, fighter planes and other instruments of warfare. While G.U.N. receives orders from the President of the United Federation, it operates under the sole discretion of the Commander, who has been known to use G.U.N.'s resources to bring down enemies.

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 * —About the Guardian Units of the Nations.

Area 99

 * Main article: Area 99

Area 99 is the first military base as well as a research facility.

G.U.N. HQ

 * Main article: G.U.N. HQ

G.U.N.'s headquarters is considered the most secure shelter in the world. The President is taken there for safety when the Black Arms attack Central City. The underground fortress is heavily guarded by three mother computers, armed security cameras, and an immeasurable number of G.U.N. troops and mechs. It is located in a mountain near the sea.

Letter of Gabriel

 * Main article: Letter of Gabriel

Prison Island

 * Main article: Prison Island

A large jungle island used as a prison and research base by G.U.N. In Adventure 2 Saga, Dr. Eggman first came there to find G.U.N.'s secret weapon, which turned out to be Shadow the Hedgehog. Some time later, Sonic the Hedgehog was captured by GUN due to a misunderstanding and imprisoned deep inside the island, but he was quickly rescued by Tails the Fox and Amy Rose the Hedgehog. At the same time Shadow, Eggman and Rouge the Bat attacked the island in order to take G.U.N.'s Chaos Emeralds. They succeeded and planted several explosives on the island, blowing it up as everyone escaped.

However, Shadow Saga revealed that the explosives had only destroyed G.U.N.'s main base and spilled toxic waste into the rivers. G.U.N. still has some overgrown paths and prison cells in the jungle, and they use them to hold captured Black Arms soldiers. Here, Charmy Bee goes to the island to look for some hidden data disks on behalf of Vector the Crocodile, to help him find them.

History
Around fifty years prior to the events of the beginning series, the GUN was been called in to deploy troops to Space Colony ARK in order to stop Project: Shadow, a research project led by Professor Gerald Robotnik that aimed to create the "Ultimate Lifeform", because the government deemed it as a threat. They apprehended most of the researchers (except for Gerald, who would be taken to Prison Island to be sentenced to execution) and stopped all their research projects before sealing the prototype of the Ultimate Lifeform away in the ARK. During the attack, a GUN soldier named Mister Schmitz caught sight of Maria Robotnik, who was helping the completed Ultimate Lifeform, Shadow the Hedgehog, escape the ARK. Schmitz pursued Maria to the escape pods, one of which Shadow had already boarded. Schmitz warned Maria he would shoot if she ejected Shadow from the ARK, but when Maria made her choice and started the escape pod's ejection sequence, Schmitz had no choice but to pull the trigger. Ever since then, Schmitz would be haunted by the guilt of having taken Maria's life.

In the aftermath, GUN would shut down the ARK for the next fifty years.