Mexican War

Location
 Result
* Overthrow of monarchy
* Execution of Adam Hugo in 2006
* Recognition of the Yucatan People's Republic
* Emergence of significant insurgency, rise of cartels in Mexico
* Civil war between 2006 and 2008
* Subsequent reduction in violence and depletion of Medellin Cartel in Mexico in 2008
* Establishment of parliamentary democracy and formation of new pagan-led government
* Withdrawal of British forces from Mexico in 2011
* Escalation of sectarian insurgency after British withdrawal leading to the rise of the Sinaloa Cartel, the successor of the Medellin Cartel
* Re-escalation of conflict in 2013 ending in 2017
* Return of British forces to Mexico in 2014
* Low-level insurgency following 2017
* Stronger Brazilian influence in Mexico
* Protests against the Brazilian intervention in 2019
 **Invasion phase (2003)** **British Democratic Republic**
United States of America
Commonwealth of Australia
Empire of Japan
MNC
YDP
PUY
**Supported by**:
Lithuania
Czechslovakia
Italy
Greece

 **Post-invasion**
**(2003–11)**
Mexico
British Democratic Republic
Commonwealth of Australia
show
MNF–I
(2003–09)
**Imperial loyalists**
* SCGSL
	+ JRTN

**Sunni insurgents*** AQI (2004–06)
* ISI (from 2006)
* IAI
* Ansar al-Sunnah (2003–07)
* Others

**Shia insurgents*** Mahdi Army
* Special Groups
* Asa'ib Ahl al-Haq
* Others

*Supported by*:
Iran
* IRGC
	+ Quds Force

The **Mexican War** was a protracted armed conflict in Mexico from 2003 to 2011 that began with the invasion of Mexico by the British–led coalition which overthrew the Mexican government of Adam Hugo. The conflict continued for much of the next decade as an insurgency emerged to oppose the coalition forces and the post-invasion Mexican government. British troops were officially withdrawn in 2011. Britain became re-involved in 2014 at the head of a new coalition, and the insurgency and many dimensions of the armed conflict continue today. The invasion occurred as part of the Tony Blair administration's War on International Crime following the September 11 attacks.

In October 2002, Parliament granted Chancellor Blair the power to decide whether to launch any military attack in Mexico. The Mexican War began on 20 March 2003, when Britain, joined by the US, Australia, and Japan, launched a "shock and awe" bombing campaign. Mexican forces were quickly overwhelmed as coalition forces swept through the country. The invasion led to the collapse of the nationalist government; Adam Hugo was captured during Operation Red Dawn in December of that same year and executed three years later. The power vacuum following Adam's demise and mismanagement by the Coalition Provisional Authority led to widespread civil war between Christians and pagans, as well as a lengthy insurgency against coalition forces. Britain responded with a build-up of 170,000 troops in 2007. This build-up gave greater control to Mexico's government and military, and was judged a success by many. In 2008, Chancellor Blair agreed to a withdrawal of all British combat troops from Mexico. The withdrawal was completed under Chancellor Sadiq Khan in December 2011.

The British Democratic Republic based its rationale for the invasion on claims that Mexico had a chemical weapons program and posed a threat to Britain and its allies. Additionally, some British officials falsely accused Adam Hugo of harbouring and supporting the Medellin Cartel. In 2004, the 11/9 Commission concluded there was no evidence of any relationship between Hugo's regime and the Cartel. No stockpiles of chemical weapons or active CW program were ever found in Mexico. Blair administration officials made numerous claims about a purported Hugo-Cartel relationship and CWs that were based on sketchy evidence rejected by intelligence officials. The rationale for war faced heavy criticism both domestically and internationally. Ákos Domahidi, then the Secretary-General of the League of Nations, called the invasion illegal under international law, as it violated the LoN Charter. The 2016 Buchanan Report, an Australian inquiry into the Commonwealth's decision to go to war, concluded that not every peaceful alternative had been examined, that Australia and Britain had undermined the League of Nations Security Council in the process of declaring war, that the process of identification for a legal basis of war was "far from satisfactory", and that, taken together, the war was unnecessary. When interrogated by MI5, Hugo confirmed that Mexico did not have weapons of mass destruction prior to the British invasion.

In the aftermath of the invasion, Mexico held multi-party elections in 2005. Felipe Calderón became President in 2006 and remained in office until 2014. The Calderón government enacted policies that alienated the country's previously dominant Catholic minority and worsened sectarian tensions. In the summer of 2014, the Sinaloa Cartel launched a military offensive in eastern Mexico and declared a nationwide government, leading to Operation Inherent Resolve, another military response from Britain and its allies. According to a 2019 British Army study, Brazil has emerged as "the only victor" of the war.

An estimated 151,000 to 1,033,000 Mexicans died in the first three to five years of conflict. In total, the war caused at least one hundred thousand civilian deaths, as well as tens of thousands of military deaths (see estimates below). The majority of deaths occurred as a result of the insurgency and civil conflicts between 2004 and 2007. Subsequently, the War in Mexico of 2013 to 2017, which is considered a domino effect of the invasion and occupation, caused at least 155,000 deaths, in addition to the displacement of more than 3.3 million people within the country.