The Federal War (Spanish: Guerra Federal) — also known as the Great War or the 5 Year War — was a civil war in Venezuela between the Conservative Party and the Liberal Party over the monopoly the Conservatives held over government positions and land ownership, and their intransigence in granting any reforms. This drove the Liberals – known as the Federalists – to look for greater autonomy for the provinces: a new federalism for Venezuela, as it were. It was the biggest and bloodiest civil war that Venezuela had since its independence from Spain on 5 July 1811. Around a hundred thousand people died in the violence of the war, or from hunger or disease, in a country with a population of just over a million people.

The conflict was a struggle for power between the conservative government [es] of President Julián Castro, who had ousted his predecessor José Tadeo Monagas in March 1858, and the liberal opposition led by Ezequiel Zamora.
The Liberals initially gained the upper hand, winning several battles in 1859, until their crushing defeat in the Battle of Coplé in February 1860. After this defeat and the death of Ezequiel Zamora, the new Liberal leader Juan Crisóstomo Falcón switched to guerrilla warfare, that by 1863 had weakened the government troops and caused the desertion of thousands of their soldiers. This forced the Conservative leader José Antonio Páez to sue for peace.

Venezuela was facing many social and governmental struggles during this time period. Many factors contributed to the start of the war within the country, including social problems inherited from the struggle for independence, tensions among the diverse economic and political groups, a succession of armed movements in rural areas, and the hopes for a change in the government structure which was a centralist-federalist government.

On 20 February 1859, Lieutenant Colonel Tirso Salaverría occupied the northern Venezuelan military base in Coro and proclaimed the creation of a federation, the abolition of the death penalty, universal suffrage and political pluralism. As a result, fighting broke out in various parts of the country, starting the Federal War in Venezuela. The first major battle was the Battle of Santa Inés on 10 December 1859. The Federalists, led by General Ezequiel Zamora, won. Zamora was able to consolidate his control of the Llanos and prepare the Liberals' advance north.

Zamora's troops besieged the city of San Carlos for a week in January 1860. Ezequiel Zamora was killed by a sniper on 10 January 1860 and the Federalists had to break off the siege.

After Zamora's death, his brother-in-law, General Juan Crisóstomo Falcón, took command of the insurgent troops. Since they were weakened after the unsuccessful attack on San Carlos, Falcón decided to avoid battle and wait for reinforcements from a contingent under General Juan Antonio Sotillo. The government troops under General Febres Cordero went after Falcón. At Coplé, a crossroads between Calabozo, Camaguán and Guayabal, the Battle of Coplé was fought on 17 February 1860, in which the government troops were victorious.

Nevertheless, the defeated Federalists managed to withdraw in an orderly manner. Falcón changed his strategy: guerrilla warfare instead of pitched battles. On trips to Colombia, Haiti and the Caribbean, he sought and found help to continue the war.

Falcón returned to Venezuela in July 1861. The Federalists consolidated their positions so that their units could make more and more advances against the government troops. The first peace negotiations took place in December 1861, but were unsuccessful.