Background
In the late 1930s, Bolivia's workers' movement made nominal political gains following the political shifts that came after the Chaco War of 1932–1935. Left-wing political parties began to displace some traditional conservative forces in the Bolivian Congress, but the government of President Enrique Peñaranda continued to pursue conservative policies. A law establishing the right to collective bargaining had been passed under the earlier government of Germán Busch, but this apparent shift on labor issues had not been tested until the 1942 miners' strike. Bolivia had formally entered World War II on the side of the Allied Powers after the Japanese attack on Pearl Harbor in December 1941, and the Peñaranda government considered wartime strikes an unacceptable disruption of Bolivian production intended for the United States.
Workers at the Catavi mine lived in poor conditions, with families housed in company huts lacking running water or toilets, and multiple families often sharing a single room. Access to health care and education was limited.
The Massacre
In 1942, workers at the Siglo XX and Catavi mines presented a petition demanding a 100% wage increase. Mine management refused to negotiate, and union leaders called for a strike. The government responded by arresting union officials, and seven miners protesting these arrests were killed. In response, 7,000 miners went on a five-day strike from 15 December to 20 December 1942. On 21 December 1942, when mine workers marched toward the management offices, the Bolivian military surrounded the crowd and opened fire for six hours.
The official government report stated that 19 people were killed and 400 wounded. Workers themselves estimated that as many as 400 people died. Among the dead was María Barzola, who was later commemorated as a martyr of the labor movement.
Aftermath
The massacre caused an open rupture in the already deteriorating relationship between President Peñaranda and both moderate and radical reform parties in the Bolivian Congress. Congress subsequently initiated a censure motion in response to the massacre, which failed by a single vote.