The Battle of Cassinga, Cassinga Raid or Kassinga Massacre was a controversial South African airborne attack on a South West Africa People's Organization (SWAPO) refugee camp and military base at the former town of Cassinga, Angola on 4 May 1978. Conducted as one of the three major actions of Operation Reindeer during the South African Border War, it was the South African Army’s first major air assault.

By the beginning of 1978 SWAPO had improved its organization and gained strength in Owambo and the Eastern Caprivi, UNITA was under pressure and it became increasingly difficult for the SADF to operate in Southern Angola. According to the South African chief of staff operations it was "imperative to deploy the full strength of the SADF's air and land capability against SWAPO, instead of counting on a 'hearts and minds' programme." South Africa also feared the disruption of elections it planned to hold in South West Africa excluding SWAPO.

The attack on Cassinga (codenamed "Moscow" by SWAPO) grew out of the plan for Operation Bruilof, which had envisaged attacking six SWAPO targets around the town of Chetequera. During the intelligence-gathering portion of the planning for Operation Bruilof, it became clear that the small, previously overlooked, one-time mining town of Cassinga was one of two SWAPO's HQ's in the region, the latter being further north at Lubango, and the principal medical centre for the guerrillas in the region.

Cassinga is a former town in the Huíla province of southern Angola.

The transliteration Kassinga is also commonly used, with the "K" being a mutation of the original Portuguese name either by German miners, or by indigenous people in whose language the letter "K" is also common. Photographs of the name in stone next to the road indicate local use the original Portuguese spelling.

Nearby is the site of an old iron ore mine once built by the Portuguese authorities and Krupp. During 1966-67 a major iron ore terminal was built in the coast by the Portuguese at Saco, the bay just 12 km north of Moçâmedes (present day Namibe). The client was the Compania Mineira do Lobito, the Lobito Mining Company, which developed an iron ore mine inland at Cassinga. The construction of the mine installations and 300 km railway were commissioned to Krupp of Germany and the modern harbour terminal to SETH, a Portuguese company owned by Hojgaard & Schultz of Denmark. The small fishing town of Moçâmedes hosted construction workers, foreign engineers and their families for 2 years. The ore terminal was completed on time within one year and the first 250,000 ton ore carrier docked and loaded with ore in 1967. After independence of Angola from Portugal in 1975, the mining facilities at Cassinga were abandoned at the start of the Angolan Civil War (1975-2002). Cassinga was also the site of the disputed Battle of Cassinga (also known as the Cassinga Massacre) (4 May 1978), a South African airborne attack on a South-West African People’s Organisation (SWAPO) military base, which was reportedly also a refugee camp of the liberation movement.