The Principality of Zeon, also referred to as the Duchy of Zeon and Zeon Dukedom, was the name adopted by the residents of Side 3 from the Republic of Zeon following the death of their former leader Zeon Zum Deikun and the succession of Degwin Zabi on August 15, U.C. 0069.
When the leader of the Republic of Zeon became gravely ill he mentioned only one name on his death bed, "Degwin Zabi". The people of Republic of Zeon took this to mean that Zeon Zum Deikun was naming Degwin to succeed him as leader of the Republic in UC 0068. After being appointed as the leader of the Republic of Zeon, Degwin Zabi adopted the title of Sodo, meaning "Lord", and was referred to from them on as Degwin Sodo Zabi. Seizing control of the government, Degwin maintained the only way for the colonies to be independent of the Earth Federation was for the Principality to fight (though in reality Side 3 was already independent of Earth at that time). To this end Degwin appointed his own children into military and political offices, and pushed for rapid development of military technology. Gihren Zabi, the eldest of the Zabi children remained at his fathers side as his aide, achieving the rank of Admiral and eventually became the Supreme Commander of the Zeon Armed Forces in place of his father. Dozle Zabi, the second eldest son of the Zabi family, became Vice Admiral and the Commander of the Zeon Space Attack Force, responsible for overseeing fleet movements within the Principality and securing areas. Kycilia Zabi, a Vice Admiral as well, shared command of the Zeon Space Attack Force with her brother Dozle, which led to conflicts between the two as she operated from the lunar city of Granada. Garma Zabi, the youngest of the Zabi family was placed in command of the Zeon Earth Attack Force. With the backing of the Principality of Zeon's new leadership, technological breakthroughs were made in a number of fields of research. One of the largest developments was that of mobile suit technology, which while originally intended for colony construction found military applications. Research by Doctor Minovsky lead to the discovery of the Minovsky Particle and the Minovsky Particle Effect, which allowed for the development of further technology, such as the Minovsky Craft System. Supported by Kycilia Zabi, research into a growing phenomenon led to the classification and discovery of Newtypes, and with her support the development of Newtype based military units.
Negotiations with the Earth Federation finally broke down in UC 0079, leading to the Principality of Zeon (re)declaring its independence from the Earth Federation and at the same time declaring war on the Federation.
One Year War
One of the first groups of colonies to be drawn into the conflict were the colonies located at Side 1, also called Zarn, which served as the capital of the Earth Federation in space. The group of colonies at Side 2 (also known as Hatte) and Side 4 (also known as Mua) were drawn into the conflict as well, with one of the devastated colonies from either Side 2 or Side 4 being used for "Operation British", which was to use a colony as a weapon by sending it on a collision course with the Earth. Operation British met with moderate success, as an explosion caused the colony to alter its trajectory and instead of impacting on the Earth based capital of the Earth Federation, it instead landed on Sydney, Australia, destroying 16% of the continent. While attempting to gain another colony to drop onto the Earth, the Earth Federation Space Forces intercepted the Zeon Space Attack Force at Side 5 (also known as Loum), resulting in the "Battle of Loum". The resulting battle employed the use of both nuclear and biological weapons, causing the complete destruction of Side 5 as both forces attempted to bring a quick end to the war. The massive loss of life at the Battle of Loum resulted in a truce being called between the Earth Federation and the Principality of Zeon in order for representatives of both governments, as well as those of other colonies, to meet and discuss the terms of the war. This meeting lead to the signing of the Antarctic Treaty, which prohibited the use of nuclear and biological weapons by both the Earth Federation and the Principality of Zeon. The treaty also outlined that colonies could not be used as weapons in the conflict, the treatment of prisoners of war, and the neutrality of other colonies that wished to remain out of the war, becoming a safe haven for refugees.
With the signing of the Antarctic Treaty, the war between the Earth Federation and the Principality of Zeon entered a new phase. Knowing that they could not continue the war without resources, the Principality of Zeon organized an assault force for the purpose of invading Earth and securing resources for the war effort. Garma Zabi, the youngest child of Degwin Zabi, was named as the Commander of the Zeon Earth Attack Force and descended to Earth with mobile suits. The invasion of the Earth proceeded quickly due to the Earth Federation Forces being ill equipped to deal with the new threat of the Zeon mobile suits, and so the Principality capturing a large number of territories and setting up mining operations as well as bases to transport materials back to the homeland. The base of operations for the Zeon Earth Attack Force was the captured California Base of the Earth Federation. The Earth Federation were however able to develop new tactics in dealing with the mobile suits, which with the aide of the Antarctic Treaty and the return of General Revil, led to a stalemate in the war as both sides worked to replenish their resources for the war and the Earth Federation gained a moral boost due to Revil's speach "Zeon is Exhausted!". However, even with the war at a stalemate, a Zeon victory seemed to be inevitable due to the high quality mobile suits being produced for both their land and space forces.
The discovery of "Project V" marked the turning point for the Zeon's war against the Federation. Till the discovery of the Federation project, the corporations within the Principality of Zeon led the way in technology and production of mobile suits. Curious and alarmed by the development of a series of Federation mobile suits, as well as a new ship in order to carry them, operations were carried out to investigate the ship codenamed the "Trojan Horse". The pursuit of the mobile suits and the ship eventually contributed to the death of Garma Zabi, as well as experienced and valuable pilots such as Ramba Ral and the Black Tri-Stars. The death of Garma Zabi on October 4, UC 0079 marked yet another turning point in the war as it led to a shake up in the political power of the Principality of Zeon. Grief stricken by the death of his youngest son, Degwin Zabi started to strongly consider moving towards a peaceful end to the war with the Federation. Degwin, however fell out of power and was now little more then a figure head as his eldest son Gihren took command of not only the military but the Principality itself. Inspired by the speech given by Gihren Zabi at his brothers funeral, the Zeon military forces fought harder in order to obtain victory and independence. Their moral boost however did not last long, as the Earth Federation started to deploy its own mobile suits on Earth and in Space, as well as carry out successful operations against the Zeon forces on Earth due to its lacking an adequate command structure with the absence of Garma Zabi. The victory of the Earth Federations "Operation Odessa" on November 9, UC 0079 started a collapse in the support infrastructure for the Zeon Earth Attack Forces.
In an effort to regain their momentum, an attack is carried out on the Earth Federation headquarters of Jaburo on November 30, UC 0079. The attack led by Captain Char Aznable succeeds in breaching the Federation Headquarters, however, due to the lack of supplies and resources at his disposal, the operation ends in failure and eventually results in a mass evacuation by Zeon forces from Earth.
With the success of operations on Earth, the Earth Federation again turned its attention and the war effort to space, which both the Earth Federation and the Principality of Zeon knew would be the final battleground for the war. Confident that the Zeon Space Attack Force can withstand anything that the Earth Federation could throw at it, Vice Admiral Dozle Zabi amassed as many ships under his command to the asteroid base of Solomon, his base of operations and a Zeon strong hold located close to Lagrange Point 5. Dozle Zabi was reluctant to ask for support from his sister Kycilia, but was able to get some reinforcements for Solomon before the Earth Federation Space Forces attacked, his reinforcements coming in the form of the MA-08 Big Zam. The added firepower of the Big Zam however was not enough to curve the tide of the Federation forces as Solomon fell with the aide of a secret Federation weapon on December 24, UC 0079, the battle ending with the abandonment of the base by the Principality of Zeon and the death of Dozle Zabi. With the loss of Solomon and a second son, Degwin Zabi started to make a move to peace, however he took notice of the shifting ideals of his eldest son Gihren. The war between the Earth Federation and the Principality of Zeon transformed under the leadership of Gihren Zabi, where instead of simple independence from the Federation, Gihren wished to destroy all human life on Earth so that the chosen race of Side 3, the Principality of Zeon can rule. Degwin departs from Side 3 in an effort to meet with General Revil, in the hopes of negotiating a peace between the Earth Federation and the Principality of Zeon before the Federation launches an attack on the last line of defense for the Principality. Knowing of the plot, Gihren orders the firing of his own secret weapon, a colony laser called the "Solar Ray". The firing of the weapon led to the destruction of a third of the Earth Federation fleet as well as the deaths of General Revil and Degwin Zabi on December 30, UC 0079.
Taking command of the remaining Zeon forces, Gihren Zabi commands from the space fortress A Baoa Qu as the remaining Federation forces launch an attack against the Zeon forces. Gihren is able to command the forces for a while, however he is executed for the assassination of Degwin by his sister Kycilia. Kycilia takes command of A Baoa Qu and oversees the battle, deploying as many mobile suits as she can in order to combat the Federation forces. Curious as to why they are taking such heavy losses Kycilia learns that a majority of the forces deployed are pilot cadets who have not yet been fully trained to pilot mobile suits. Determining that the battle is lost, Kycilia gives the order to have her ship ready to depart and for the remaining forces to surrender once she has left with an escort group. The command however is never issued as the command center was over run by Federation forces that gained entry to the fortress, and Kycilia was assassinated by Char Aznable, her ship destroyed not long after.
With a lack of command and control, the remaining Zeon fleet went into a panic. Split as to what to do a number of ships gathered as many as they could before fleeing the battlefield, while others remained to fight to the last man, each believing that it was what their commanders wanted. With the fall of A Baou Qu, the remaining government of the Principality of Zeon surrendered to the Earth Federation, bringing an end to the war on January 1, UC 0080.