The deadliest war in North America's modern history started 105 years ago today

The Mexican Revolution, which began on 105 years ago and raged for a decade, is considered to be the first major social, political, and cultural revolution of the 20th century, and perhaps the bloodiest conflict in modern North American history.

The revolution resulted in more than 1.5 million deaths. Hundreds of thousands of Mexican refugees fled to the US. A cascade of leaders rose to prominence - only to be assassinated. Peasant uprisings broke out throughout the country that was in a decade-long state of crisis.

At the heart of the revolution were tensions between the "criollos," or the Spanish-descended ruling class, and "mestizos," or people of mixed Spanish and indigenous ancestry that comprised a majority of the population and much of the country's peasantry. Mexico in the years leading up to the revolution was a powder keg, with elites facing off over questions of presidential succession and constitutional change, and the peasantry feeling increasingly angry and alienated.

Mexico was in need of fundamental changes - changes that weren't likely to change peacefully.

Tensions came to a head when Porfirio Diaz, the dictator who had rule Mexico for the previous 34 years, sought to continue his rule for an eighth term as president.

Francisco I. Madero, a Mexican political exile wrote and distributed the "Plan of San Luis Potosí," which, among other things, called for a revolution beginning on November 20, 1910, to depose Diaz and restore both the 1857 constitution and the term limits that it mandated.

Though Madero's pen initiated the revolution, reival generals, political figures, and militia leaders, the most famous of which were Pancho Villa in the north and Emiliano Zapata in the south, carried out most of the fighting.

Zapata was especially emblematic of the revolution. A champion of the "campesinos," or country people of Mexico, Zapata's rallying cry of "Tierra y libertad" (Land and Liberty) galvanized the rural poor - a population that wanted sweeping change.

Zapata helped draft a counter to the Plan of San Luis Potosí, known as the Plan of Alaya. Under this proposal, land would be redistributed to the peasants who worked on it. Zapata's plan for "land for those who work it" proved popular with campesinos.

By May of 1911, Diaz had left the country. But after 35 years of a single dictator, Mexico found itself trapped in a destructive power vacuum. Madero ruled briefly before being assassinated in 1913 by Victoriano Huerta, a general in league with counterrevolutionaries led by Porfirio Díaz's nephew.

Amid heavy opposition, Huerta dissolved Mexico's congress and began to impose an autocratic government similar to Diaz's. US President Woodrow Wilson soon sent Marines into the country to remove Huerta.

After US forces helped oust Huerta in 1914, Washington settled on supporting Venustiano Carranza, a wealthy landowner.

At first, Carranza sought to reconcile the differences of the different camps. Carranza's US-backed government eventually endorsed and drafted a new constitution that was approved in 1917.

The constitution included agrarian reform and expanded individual rights. But Carranza left many of his promises unfulfilled, and was assassinated while fleeing Mexico City during the next election, in 1920.

Alvaro Obregon, a one-time ally of Carranza's who later helped overthrow him, became president in 1920, an event that marked the end of over a decade of instability and vioelnce.

Mexico was in continuous turmoil throughout this period. The revolution was a complex and multi-sided conflict that pitted the country's rulers against one another - and against a peasantry eager for political and social change.

While Mexico is now a democracy, the revolution didn't exactly end that way. In 1929, the Institutional Revolutionary Party came to power. Implementing a system often described as a "benign dictatorship," the party would remain in charge of Mexico until Vicente Fox's election 2000.