Scarecrow's Army

Scarecrow's Army is a massive uniting of all of Gotham's criminals. Originally it was merely Scarecrow's Gang before the uniting of the criminals.

Leadership

 * Dr. Jonathan Crane/Scarecrow - Leader
 * Jason Todd/The Arkham Knight - First commander of militia in a partnership with Scarecrow
 * Slade Wilson/Deathstroke - Second commander of militia, campaign overseer, took over the militia after Arkham Knight's defeat

Lieutenants

 * Dr Harleen Quinzel/Harley Quinn - Conscripted by Scarecrow to infiltrate Blüdhaven Police Station to secure the release of Poison Ivy.
 * Harvey Dent/Two-Face - Bank Robber.
 * Oswald Cobblepott/Penguin - Gun runner and weapon supplier.
 * Edward Nigma/Riddler - Intelligence.

Henchmen

 * Scarecrow's Henchmen
 * Arkham Knight's Army
 * Harley's Thugs
 * Two-Face's Gang
 * The Penguin's Henchmen
 * Riddler Thugs
 * Thugs

Other Possible Affiliations

 * Jervis Tetch/Mad Hatter - Managed to acquire Fear Gas, so is likely affiliated.
 * Dr. Thomas Elliot/Hush - Doppelgänger of Bruce Wayne to discredit him. Fear Gas canisters were found at his hideout in Arkham City.
 * Garfield Lynns/Firefly - Arsonist. Wanted revenge against the firefighters of Station 17. But might be also assisting or working with the Scarecrow.

Gear and weaponry

 * Numerous guns and melee weapons
 * Arkham Knight's Drones
 * Fear Gas
 * Two-Face's Dual Pistols
 * Penguin's Umbrella
 * Pipe
 * Baseball Bat
 * Knife
 * Sword
 * Handgun
 * Assault Rifle
 * Sniper Rifle

Locations

 * Arkham Asylum
 * Amusement Mile Docks
 * Gotham City

Between Arkham Asylum and Arkham Knight
Scarecrow was brutally mauled by Killer Croc at Arkham Asylum and planned revenge at Batman. For countless months, Scarecrow wanted to attack Gotham City and unmask Batman. Scarecrow came across the mysterious Arkham Knight who wanted to kill Batman and use an army. Scarecrow didn't want the Knight to kill Batman but both of them began an alliance. Deathstroke joined as well since he helped the Arkham Knight assemble the militia as he was the "toughest bastard who faced the Bat". Deathstroke had been chosen to oversee their campaign and serve as a backup commander if the Knight is done for.

Arkham Knight Incident
Late night on October 30th, Scarecrow's army made their first move. The Arkham Knight went to Pauli's Diner, with a bag containing five ounces of Fear Toxin. He let it out, fleeing before he could be affected. Scarecrow then made a public broadcast, demanding that all of Gotham's better citizens leave the city or he would detonate a bomb of his Fear Toxin. After a mass evacuation, the city was left with only Scarecrow's Army, GCPD and the Bat Family on Halloween.

Scarecrow allowed the gangs to do as they wished, not caring for their well being if he detonated his Fear Gas. Eventually, all members of the army were defeated and taken to GCPD, except the Knight, who became the murderous vigilante Red Hood.

Trivia

 * All three leaders wanted to attack Batman but for different purposes.
 * Scarecrow: Wants to unmask the Batman so that his legend dies.
 * Arkham Knight: Wants to kill Batman after being tortured by Joker.
 * Deathstroke: Wants to assassinate Batman for cash and to get revenge for being beaten by him during the events of Batman: Arkham Origins.