White Zetsu Army

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

Background
According to Sakura's and Shizune's research, the White Zetsu Army soldiers are copies of the First Hokage. More precisely, they are moving clone plants, created by cultivating the First Hokage's cells and using certain plants as a medium. Tobi created the Zetsu army using the chakra of the first seven tailed beasts, using a clone of the First to connect the Demonic Statue of the Outer Path - which the tailed beasts were sealed within - to a cavern beneath Mountains' Graveyard where the army was made and stored. After Kabuto Yakushi captured Yamato, he used his studies of Hashirama's DNA and Yamato to improve 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 angered when they realised that Sasuke had killed their original.

Appearance
Unlike the original white side, which is only half of a Zetsu; they have complete faces with properly defined right arms and legs. After Kabuto uses Yamato to further enhance their abilities, the Zetsu 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
As the main force of Akatsuki's army, the White Zetsu are presumably adept for combat. With Kabuto's offer of increasing their strength, they might be even stronger than before. Like the original Zetsu, they are able to use Mayfly to travel underground. They are also extremely durable, able to survive two attacks from Sakura, as well as Neji's Gentle Fist Art One Blow Body, and seem to have limited regenerative abilities. They can open their bodies in a Venus flytrap-like manner to trap their opponent and absorb their chakra. Like the original White Zetsu, they are also able to use the Substitute Technique. In the anime, they could also extend the sharped points of their flytrap-like extensions and use them to pierce and impale enemies.

Their capacity to absorb chakra serves a more sinister purpose: to allow any active Zetsu Army soldier to take on the appearance and chakra signature of the person they latched on. With this ability, they can deceive anyone into gaining the trust of the copied person's acquaintances, deceiving even the best sensors. Such an ability is perfect for espionage and covert assassination. These Zetsu are also able to merge with each other to form a mutated version of themselves that resemble fly-traps even more. By merging, it apparently makes them somewhat more resilient. Due to the fact that they were created through cultivation of Hashirama Senju's cells, Sakura states that they can also use Wood Release, albeit on a weaker scale. A downside to their genetics is that, once they come into contact with a powerful concentration of Yang-natured chakra, it affects them directly causing them to turn into trees.

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 Zetsus travelling directly underneath them. While fighting the Allied Shinobi forces, they began to overwhelm them. Several thousand White Zetsus passed through the Allied Forces in the underground.

Then, off the coast of the Land of Lightning, several thousand White Zetsu 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, Zetsu Army soldiers used the Substitute Technique to sneak behind enemy lines disguised as allied shinobi, and kill various members of the Allied Shinobi Forces. After Sakura Haruno discovered and stopped one of them, who had transformed into Neji Hyūga, the technique was deduced and it was reported to HQ. When Naruto and B confronted several of these clones, due to Naruto's Yang chakra and the nature of the Zetsu, when he attacked them they all turned into trees. This was due to the fact that because they were made from the First Hokage's cells they resonated with the life force energy of Naruto's Nine-Tails Chakra Mode in a similar manner to Yamato's Wood Release did in the Tailed Beast Temple. Even after they merge to try to become more resilient, Naruto merely cuts them in two and crushed them with Gamahiro.

Naruto eventually sends out his clones out to the different battlefields and using his abillity to sense negative emotions he was able to locate the remainders of the disguised Zetsu.

After the second day of war, thanks to the addition of Naruto's efforts and his newfound ability, the majority of the White Zetsu clones are eradicated. However small factions have seemingly survived and were ordered to seize Killer B and Naruto before his comrades could get to where he was. When Sasuke escaped the Mountains' Graveyard, he encountered one of these factions who demanded to know why he left the hideout. When the clones realise he killed the original White Zetsu, they attack him. Choosing this time to test his new powers further, he slaughters most of the clones before using a genjutsu on a surviving one 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 and another escaping one before heading towards the battlefield to kill Naruto himself.