The Rebellion

"I didn't fight a one thousand-year war for this planet's independence to take orders from the likes of you!"

The Rebellion or the "Gem War" was an event that occurred approximately 5,750 years ago, according to Garnet, when the Crystal Gems rebelled against the Gem Homeworld to protect Earth. According to Pearl, the war lasted approximately 1000 years. The war ended with the diamonds setting off a weapon that corrupted every unprotected gem that remained on Earth, in a last-ditch effort to win the war. Ultimately, the Crystal Gems emerged victorious.

History
Over 6,000 years ago, the Gem race started colonizing the Earth under Pink Diamond's jurisdiction. She made her base on Earth's moon. One of the colonizers was the Centipeetle Mother, who came to Earth on board the Ancient Gem Colony Ship along with the rest of her crew, ordered by an unnamed commander.

As they landed on Earth, many Gem structuers were erected, the first being Kindergartens. The kindergartens started to incubate Quartz soldiers first; including Rose Quartz in an unknown Kindergarten, Amethyst in the Prime Kindergarten, and Jasper in the Beta Kindergarten. As the Gems were incubated, gathering minerals off of the Earth's crust, many other Gem structures were erected inlcuding the Lunar Sea Spire, the Sky Spire, the Ancient Sky Arena, among many more.

Homeworld Gems wanted to colonize Earth and erect more spires and Kindergartens, but would in turn strip the entire planet of it's resources virtually erasing all pre-existing life on Earth. However, Rose Quartz saw that every life was important and was worth protecting.

Still in the process of colonizing Earth, Rose Quartz, started a rebellion. Ruby (eyeball) stated that it was during the rebellion that Jasper popped out of the ground and defeated multiple rebel troops, Jasper herself told a similar story in that she was on Earth fighting against Rose's army. Homeworld tried to supply itself with soldiers by rushing the production in the Beta Kindergarten.

During the rebellion, Rose managed to shatter Pink Diamond, with Ruby (eyeball) stating that she was there and had witnessed it, effectively starting an all out war with Homeworld; with Rose giving her army the name of Crystal Gems. She had shattered Pink Diamond to liberate the Earth from Homeworld's clutches. Homeworld Gems wanted to do something bad to the Earth, and some Gems, such as Pearl, Garnet, and Rose Quartz found their proposals unfair to the life already existing on the Earth, and it was this that had spurred Rose to rebel against her kind and the rest of the Crystal Gems to follow her.

The Homeworld colonization of Earth wasn't finished, but this time under Blue Diamond's jurisdiction. While on Earth, Blue Diamond summoned one of her court members, Sapphire, protected by three Ruby bodyguards, one of which was Ruby herself. Sapphire had been summoned to use her Future Vision and guide Blue Diamond and her court in the right course of action that would end in the defeat the rebels and win them the war.

During a two-Gem raid by Rose and Pearl moments later, Ruby fused with Sapphire by accident as she tried to save her to form Garnet for the very first time, causing Sapphire's prediction to fail. After the two rebels flee the scene, Blue Diamond demands Ruby be "shattered" for the incident. Sapphire reacts by grabbing Ruby and jumping out of the arena towards the ground. Over an unknown period of time, Ruby and Sapphire develop a romantic relationship and fuse once again. After running into Rose and Pearl again in a chance encounter, Ruby and Sapphire as Garnet joined the Crystal Gems' rebellion.

The earliest battles in the war for Earth occurred in the Ancient Sky Arena. With the ancient Gem Battlefield, having described by present day Garnet as, a horrible site where countless Gems were broken in a maelstrom of death and destruction during the fight.

Lapis Lazuli visited Earth for, supposedly, a short time but was caught somewhere in the middle of the war. As she tried to escape, she was poofed by one of the rebels. Her gemstone was then picked up by a Homeworld soldier. She was placed on a mirror as she was confused for one of the rebel Gems and used as a tool to try and extract information on the rebels. But since she wasn't a Crystal Gem, she didn't know and she couldn't voice out, and was eventually forgotten.

In another place, still during the war, Bismuth, a Gem whose purpose was to build structures for Homeworld but was now a rebel and instead made weapons for the Crystal Gems, had a disagreement with Rose Quartz about a weapon she had made that could end the war but at the cost of shattering her enemies' gemstones. Rose, seeing value in all life, including her enemies, disagreed with Bismuth's means of ending the war. The two fought beneath the forge with Rose having come out as the victor and Bismuth's gem having been bubbled and placed inside Lion's mane.

Somewhere near the end of the war, Homeworld decided to do some fusion experiments. Using the shattered remains of both ally and enemy gems, they forcibly fused multiple shards together and incubated them below the Prime Kindergarten without the Crystal Gems finding out. The end goal of the experiment was to make the Cluster, a massive forced fusion of millions of Gem shards. Having been inserted deep within the Earth's mantle with the Beta Kindergarten being it's insertion point.

Nearly a thousand years later, Homewrold was losing the war. As a final ditch effort on eliminating the rebels. Homeworld had sent out an order to all allied Gems on earth to leave. The Centipeetle Mother was separated fro her crew amongst the chaos. As the Centipeetle Mother looked up to the sky, she could see many ships going off planet, leaving her behind.

In the Galazy Warp, countless Homeworld Gems were scurrying to get to the warp pads and leave Earth. As the Gems ran for the warp pads, the mirror that held Lapis fell on the ground. As it lay there, one Gem stepped directly on her gemstone which caused it to crack. Lapis, at the now empty Galaxy Warp, was stuck to a mirror, broken, and was left on the ground unable to move.

Then the remaining three Diamonds sent out a light as seen in Lapis' projection. Centipeetle Mother described as a sound or a song. The light had corrupted the remaining unprotected Gems on Earth as a final attack on the rebels.

The only Gems that survived the attack unscathed and winning the war were Rose Quartz, Garnet, Pearl, Bismuth; who had been previously bubbled by Rose to prevent her from enacting her plan; and Lapis Lazuli who was still trapped in the mirror. Greg had said that Rose could only save a handful of her friends.

Aftermath
With Pink Diamond no longer in commission, the Gems that served under her court were reassigned to the other three Diamonds, with Jasper now under Yellow Diamond's court.

Sometime after the war, Rose Quartz found a Quartz soldier, Amethyst, in the Prime Kindergarten. She was shorter than what she was supposed to be, due to her prolonged incubation time beneath the earth. Amethyst joined the Crystal Gems. She was also unaffected by the corrupting light.

The areas around where the Kindergartens were built were now seemingly permanently barren. No form of organic life could live there. As seen in "On The Run" as Amethyst and Steven drew near the Prime Kindergarten, the plantlife just stops abruptly with little to no form of transition, from grassy ground to barren dirt.

After the corrupting light was sent out, the Earth was now riddled with corrupted Gems that run amock. The remaining Crystal Gems took it upon themselves to subdue the corrupted Gems until they could cure them, bubbling them and keeping them inside the Crystal Temple.

Most of the Gem structures that were built were now in a state of disrepair. Some of which showed signs of battle. Others were continually crumbling away as time passed by. The Gem Battle field were the Crystal Gems had fought and where the Pyramid Temple was located, was overrun by a massive growth of strawberries, earning the second name of Strawberry Battlefield. Many material weapons are still scattered around the battlefield.

Trivia

 * Sets of armor are seen that Pearl refers to as "The Armor of the Fallen" in Rose's Secret Armory; it is possible that the armor belongs to the deceased Gems during the Rebellion.
 * However, the majority of Gems did not use external armor (aside from weapons similar to Jasper's Helmet that could be summoned and dismissed at will). Greg Universe told Steven that both Gems and Humans were involved in the Rebellion so the armor of the Fallen might belong to Human warriors that died in battle fighting alongside Rose Quartz.
 * It is initially implied that Amethyst was about 500 years old at the time of the Rebellion, but it is later stated by Steven that she did not "come out of the ground" until the Rebellion was over, which might indicate that she was still incubating during the event of the war., page 39 "...she didn't come out of the ground until after Garnet and Pearl and Mom were already done fighting the earth war." Amethyst never experienced the war, though she has said that she wishes she could have been a part of it.
 * Greg said the Rebellion ended with Gems and people being destroyed, indicating humans might have been involved in the Rebellion or some humans were unfortunate victims of it.
 * Pearl confirms that the Crystal Gems used the Wailing Stone during the Rebellion to communicate in "Rose's Room".
 * Pearl states that the Rebellion lasted roughly one thousand years.
 * It seems that the knowledge about of the Rebellion was either restricted, or openly discouraged on Homeworld; in Marble Madness, Peridot didn't know that any Gems exist on Earth at all, and clearly didn't understand who the Crystal Gems were supposed to be, and why they are trying to interfere with her activities.