The Easter Offensive, also known as the 1972 spring–summer offensive (Vietnamese: Chiến dịch Xuân–Hè 1972) by North Vietnam, or the Red Fiery Summer (Mùa hè đỏ lửa) as romanticized in South Vietnamese literature, was a military campaign conducted by the People's Army of Vietnam (PAVN, the regular army of communist North Vietnam) against the Army of the Republic of Vietnam (ARVN, the regular army of South Vietnam) and the United States military between 30 March and 22 October 1972, during the Vietnam War.

This conventional invasion (the largest invasion since 300,000 Chinese troops had crossed the Yalu River into North Korea during the Korean War) was a radical departure from previous North Vietnamese offensives. The offensive was designed to achieve a decisive victory, which even if it did not lead to the collapse of South Vietnam, would greatly improve the North's negotiating position at the Paris Peace Accords.

The U.S. high command had been expecting an attack in 1972 but the size and ferocity of the assault caught the defenders off balance, because the attackers struck on three fronts simultaneously, with the bulk of the PAVN. This first attempt by North Vietnam to invade the south since the Tet Offensive of 1968, became characterized by conventional infantry–armor assaults backed by heavy artillery, with both sides fielding the latest in technological advances in weapons systems.

In the I Corps Tactical Zone, North Vietnamese forces overran the ARVN’s defensive positions in a month-long battle and captured Quảng Trị city, before moving south in an attempt to seize Huế. The PAVN similarly eliminated frontier defense forces in the II Corps Tactical Zone and advanced towards the provincial capital of Kon Tum, threatening to open a way to the sea, which would have split South Vietnam in two. Northeast of Saigon, in the III Corps Tactical Zone, PAVN forces overran Lộc Ninh and advanced to assault the capital of Bình Long Province at An Lộc.

The campaign can be divided into three phases: April was a month of PAVN advances; May became a period of equilibrium; in June and July the South Vietnamese forces counter-attacked, culminating in the recapture of Quảng Trị City in September. On all three fronts, initial North Vietnamese successes were hampered by high casualties, lack of fuel and the increasing application of U.S. and South Vietnamese air power. One result of the offensive was the launching of Operation Linebacker, the first sustained bombing of North Vietnam by the U.S. since November 1968. Although South Vietnamese forces withstood their greatest trial thus far in the conflict, as well as thwarting North Vietnam's goal of large territorial gains, the North Vietnamese accomplished two important goals: they had gained valuable territory within South Vietnam from which to launch future offensives and they had obtained a better bargaining position at the peace negotiations being conducted in Paris.

Despite repulsing the PAVN offensive, the ARVN victory was only achieved through with massive U.S. air support.

In the wake of the failed South Vietnamese Operation Lam Son 719, the Hanoi leadership began discussing a possible offensive during the 19th Plenum of the Central Committee of the Vietnam Workers' Party in early 1971. Convinced that they had destroyed South Vietnam's best units during Lam Son 719, by December, the Politburo had decided to launch a major offensive early in the following year. 1972 would be a U.S. presidential election year, and the possibility of affecting the outcome was enticing and there was increasing anti-war sentiment among the population and government of the U.S. With American troop withdrawals, South Vietnamese forces were stretched to breaking point along a border of more than 600 miles (966 km) and the poor performance of ARVN troops in the offensive into Laos promised an easy victory.

This decision marked the end of three years of political infighting between two factions within the Politburo: those members grouped around Trường Chinh, who favored following the Chinese model of continued low-intensity guerrilla warfare and rebuilding the north, and the "southern firsters" around Defense Minister Võ Nguyên Giáp, supported by First Party Secretary Lê Duẩn (both of whom supported the Soviet model of big offensives). The failure of the Tet Offensive of 1968 had led to a downgrading of Giáp's influence, but the victory achieved over South Vietnamese forces during the Laotian incursion brought Giáp's strategy back into the ascendant. Lê Duẩn was given responsibility for planning the operation but Giáp never rose to his former prominence, dealing chiefly with logistical matters and the approval of operational planning. The officer entrusted with the conduct of the offensive was the PAVN chief of staff, General Văn Tiến Dũng.