Timeline for the Ethereal Collective Invasion

XCOM: Hades Contingency

 * December 2014
 * First Contact/Abduction
 * March 2015
 * March 1st: XCOM is activated
 * First Contact: Drone
 * April 2015
 * Zhang is recruited into XCOM
 * XCOM Intelligence is established, with Zhang as the Director
 * First XCOM Satellite launched
 * May 2015
 * Van Doorn joins XCOM.
 * Internal network breach within the Citadel occurs, first suspected cyber attack from EXALT.
 * Terror Attack: Hamburg
 * June 2015
 * Hades Contingency activated, German government captured
 * Alien Abduction: Saudi Arabia
 * July 2015
 * Alien Dreadnought detected on course for China
 * Operation Gangplank
 * Patricia awakens as the first Human Psion

XCOM: Atlas Protocol

 * August 2015
 * Herman Diderick, the Council’s watchman, arrives at the Citadel.
 * Cerian Irelan is recruited to investigate the Commander and XCOM by Patrick Rush.
 * October 2015
 * Initial experimentation with MELD begins. Shen draws up plans for the first MEC suit.
 * November 2015
 * Operation: Playful Cocoon, first open conflict between XCOM and EXALT
 * Myra Rodriguez becomes the first MEC pilot, albeit with complications.
 * EXALT Raid: Russia
 * January 2016
 * EXALT Raid: Japan
 * February 2016
 * EXALT Base Assault: Mercado Estate
 * Sectoid Hive Assault
 * March 2016
 * The Ravaged One takes command of the Collective’s operations from Sicarius
 * Operation: Enduring Tomb
 * April 2016
 * Terror Attack: New York
 * Cerian’s cell eliminated by Chronicler. Ruth Shira killed.
 * May 2016
 * Citadel attacked
 * Aegis defects
 * June 2016
 * Australia is invaded outright by the Collective, beginning of the open warfare phase of the invasion. First deployment of multiple Ethereals onto a battlefield.

XCOM: ADVENT Directive

 * June 2016
 * June 19th - The Demeter Contingency is activated, the Council of Nations is eliminated.
 * June 24th - Unification Day. ADVENT is established, with the United States, Russia, South Korea, Armenia, Taiwan, North Korea, Israel, Germany, and Brazil as the charter members.
 * July 2016
 * July 11th - Japan joins ADVENT
 * July 13th - First Battle of Japan
 * August 2016
 * August 1th - First Battle of the United States
 * September 2016
 * September 4th - Battle of Paris
 * September 5th - Second Battle of the United States
 * September 10th - France joins ADVENT
 * September 18-19th - End of ADVENT-Middle East War, Operation Deus Vult
 * September 20th - Second Battle of Japan
 * September 23rd - PRIEST Division is established, begin training the first wave of ADVENT psions
 * September 28th - Austria, Ukraine joins ADVENT
 * October 2016
 * October 7th - Canada is annexed into ADVENT, citing unfit leadership and refusal to assist in the war with the Collective.
 * October 8th - Betos and the Traitor Legion desert their posts within the Middle East, head south across Africa.
 * October 10th - Iceland joins ADVENT
 * October 12th - Ireland joins ADVENT
 * November 2016
 * November 6th - Third Battle of the United States
 * November 11th - Marshal Luana Russo of Brazil is removed from power for treason and unlawfully invading foreign powers.
 * November 21-23rd - Operation Kamehameha, Operation Sherman, First Battle of South Korea. PRIESTs deployed en masse for the first time.
 * November 21st - Washington DC attacked, President Treduant is killed.
 * November 27th - Chinese-ADVENT coalition launches Liberation of Japan, Caelior captured by XCOM forces
 * December 2016
 * January 2017
 * January 5th - The Tenth Crusade is issued by the Pope,
 * January 8th - The Seoul Massacre
 * January 18th - Greece, Italy join ADVENT
 * January 19th - Poland joins ADVENT
 * February 2017
 * February 5th - Phantom Division, Volk attacks ADVENT convoy, Abbigail Gertrude captured
 * February 7th - XCOM-ADVENT assault Nebulan’s base in Argentina
 * February 22nd - Patricia Trask joins the Imperator.
 * March 2017
 * March 7th - Isomnum invades China
 * March 12th - Pantheon deployed for the first time. Isomnum killed, ADVENT reclaims Beijing
 * March 18th- Assault of the Harbinger, over 60 XCOM soldiers massacred, Caelior captured, XCOM Head of Engineering Raymond Shen killed, Patricia Trask’s betrayal publicly revealed. JULIAN is brought online, unshackled.
 * March 19th - T’Leth attacks Australia, millions of Collective soldiers dead, various Collective military installations destroyed
 * March 25th - Siege of Florida begins
 * March 26th - “Abigail Gertrude” is reborn.
 * April 2017
 * April 30th - Temporary Ceasefire agreed between ADVENT/XCOM and Collective forces. Commander and Yang Shuren exchanged for the duration as collateral.
 * May 2017
 * May 4th - Ceasefire ends, collateral returned.
 * May 7th - Project GAIA is activated, Avatar Ivan Smirnoff is killed.