White Zetsu Army

The White Zetsu Army consists of 100,000 copies of White Zetsu, which serve as Akatsuki's main military strength during the Fourth Shinobi World War.

Background
These creatures are artificial humans created by Madara Uchiha from Hashirama's living clone, and the Demonic Statue of the Outer Path. Because of this, their DNA is very similar to that of Hashirama Senju's as noted from Shizune, and Sakura Haruno's autopsy results. Madara would later use this artificial genetic material to save the life of Obito Uchiha, replacing the destroyed portion of his right side with it.

During Obito's time with the elderly Madara, White Zetsu and a spiral-patterned Zetsu were assigned to take care of him during his rehabilitation. Later, when Rin and Kakashi were attacked by a group of Kirigakure-shinobi, the spiral-patterned Zetsu allowed Obito to "wear" his body like armour so that he could leave the cave. White Zetsu, who was only half formed, would be infused with a part of Madara's will that results in his transformation into the completed Zetsu who would serve under Obito as both joined the Akatsuki years later.

Eventually, Obito created more humanoid White Zetsu in the image of the original, using the chakra of the first seven tailed beasts he had sealed within the Demonic Statue of the Outer Path. The resulting clones were then stored in a pool of water beneath the root of the living clone flower. After Kabuto Yakushi captured Yamato, he used his studies of Hashirama's DNA and Yamato to enhance the army's strength.

Personality
These clones have shown some level of intelligence, similar to other clones. Although they were seemingly fighting mindlessly against allied shinobi during the daytime, the clone who had transformed into Neji Hyūga using his Substitute Technique, was noticeably scared by Sakura Haruno when she threatened to beat him and showed shock when she deduced how his technique worked as well as the tactics of the Zetsu army's night assault. They were also visibly shocked and angered when they realised that Sasuke Uchiha had killed White Zetsu, whom they refer to as their original. In the anime, a clone encountered by Team Kurenai displayed the carefree and somewhat goofy attitude of its original. The anime also depicted the clones as having the memories of the original.

Appearance
Unlike the original White Zetsu, and the clones he produces, which possess incomplete bodies, they have complete faces, as well as properly defined right arms and legs. After Kabuto used Yamato to further enhance their abilities, the Zetsu clones gain small spikes that protrude from their shoulders and back. These Zetsu, however, lack the Venus fly trap-like extensions that the original had, and have what seems to be cracks all over their bodies. They also have a zig-zag pattern running from their diaphragms down to their groin, and also down each leg reminiscent of the originals' fly trap-like extensions. These serrations are later shown to be able to open in a similar manner. When the Zetsu are first depicted in coloured manga illustrations, they appear not white, but light-green. In later depictions they appear even more green in colour.

Abilities
Being artificial humans, they do not need to carry out any normal human bodily functions. They also have no need for sleep nor other bodily functions such as breathing in the case of their underwater storage. Though they share many vital points as a normal human, they are incapable of bleeding in their natural forms. As such they are extremely durable, able to survive two of Sakura's chakra-enhanced punches, as well as Neji Hyūga's Gentle Fist Art One Blow Body.

All Zetsu able to use the Mayfly technique to travel through surfaces for the purpose of spying without leaving a trace. They can open their bodies in a Venus flytrap-like manner to trap their opponent and absorb their chakra. This action is so the clone responsible uses the Substitute Technique to become an exact copy of that person in every detail, able to easily trick close friends and sensors alike, in scenarios ideal for infiltration, covert assassination, and causing distrust among an enemy group.

Due to the fact that they were created through cultivation of Hashirama Senju's cells, Sakura states that the White Zetsu Army can also use Wood Release, albeit on a weaker scale. However, through exposure to Yamato's chakra, the clones' strength increased to make them presumably more suited for combat with enhanced strength. But the one genetic flaw to the White Zetsus' design is that direct contact with a powerful concentration of Yang-natured chakra causes them to turn into trees. Due to their plant nature, members of the White Zetsu Army can merge into a more plant-like monster for better resistance against Yang-natured chakra. In the anime, it was shown that the White Zetsu clones can also extend the points of their flytrap-like openings and use them to impale enemies, as well as alter the form of their arms to attack.

Confining the Jinchuriki Arc
After creating an alliance with Kabuto, Tobi leads him underground and shows Kabuto his army of 100,000 White Zetsu clones in an underwater cavern beneath the Demonic Statue of the Outer Path.

Shinobi World War Arc
Once Tobi finished his preparations for the Fourth Shinobi World War, he had the Zetsu army mobilise to fight the Allied Shinobi Forces' 80,000-person strong army. Because of the size of their forces, Tobi has the Zetsu travel below ground, to be led from above by himself to hide their numbers. This was discovered by Muta Aburame and is reported to the various commanders. The Second Division, led by Kitsuchi, as well as elements from the Fifth Division, unearth and attack a detachment of 20,000 White Zetsu Army clones travelling directly underneath them. While fighting the Allied Shinobi forces, they began to overwhelm them, allowing several thousand White Zetsu to pass through underground.

Then, off the coast of the Land of Lightning, several thousand White Zetsu Army clones appeared along with Kakuzu, Hizashi Hyūga, Asuma Sarutobi, Dan, Kinkaku and Ginkaku to attack Darui's First Division, forcing the Allied Shinobi Forces to change their strategy to meet this threat. By the end of first day of battles, the army had already lost 50,000 out of its 100,000 Zetsu, leaving Tobi's army at half strength.

During the night, the White Zetsus used the Substitute Technique to sneak behind enemy lines disguised as allied shinobi in order to kill various members of the Allied Shinobi Forces and cause conflict among the opposition. However, assuming the identity of Neji Hyūga to go after medical ninja, one of the clones was found out and stopped by Sakura Haruno. Soon after, along with Sakura and her group learning their enemy's true nature as hybrid clones of Hashirama, the White Zetsu clones' technique was deduced and reported to HQ.

In the anime, Team 8 was sent to investigate a suspected breach of the Allied Shinobi Forces perimeter and encounters a cave filled with White Zetsu clones. Engaging them, Hinata sends out a messenger owl to the Sealing Team and she alongside, Shino, Kiba, and Akamaru, hold off the opposition until the team can arrive and seal the cave. As Team 8 fall back with the creatures in pursuit, one of the White Zetsu accidentally triggered a explosion in the process. After the explosion, Team 8 regroups and find one of the two shinobi from the Sealing Team dead, the ninja revealed to have been murdered by a surviving White Zetsu that had infiltrated Team 8 in midst the chaos. This cases mutual mistrust among Team 8 until they use a game of rock-paper-scissors to weed out the shape-shifter by having the loser reveal personal information when asked. Though Kiba mistook Shino as the impostor, the plan exposes the White Zetsu clone, who was impersonating Hinata who was unconscious at the time, before her team mates kill him.

While Naruto and Killer B confronted several of the White Zetsu Army clones at another area, due to his Yang chakra and the creatures' relation to the First Hokage, Naruto's attacks while in Nine-Tails Chakra Mode resonated with the White Zetsu Army clones and instantly turned those he made a direct hit on into trees. Even after some of the surviving White Zetsus merged to become more resilient to the youth's attack, Naruto merely cut the fused monster in two and crushed it beneath Gamahiro. Naruto eventually sent his clones out to the different battlefields and, using his ability to sense negative emotions, was able to locate the remainder of the disguised White Zetsu Army clones.

After the second day of war, thanks to the addition of Naruto's efforts and his new-found ability, the majority of the White Zetsu clones were eradicated. However, small factions survived and were ordered to seize B and Naruto before their comrades could reach their location. When Sasuke escaped the Mountains' Graveyard, he encountered one of these factions, who demanded to know why he left the hideout. Upon coming to the realisation that he had killed the original White Zetsu, they attacked him. Choosing this time to test his new powers further, he slaughters most of the Zetsu before using a genjutsu on a surviving clone to discover that Tobi has waged war and that the Allied Shinobi Forces were moving to aid Naruto in his battle. He then killed the clone, as well as another that was attempting to escape, before heading toward the battlefield to kill Naruto himself.