In the 1930s, the Salazar government instituted tariffs on Angola to limit investment from Portugal's colonial competitors while investing in Angola's infrastructure to increase exports to Portugal. Angolans completed the construction of the Benguela railway in 1929 and opened it to transportation in 1931. The railway facilitated the exportation of minerals mined in Belgian-ruled Katanga through Angola's western ports.[5] The South African Oppenheimer Trust produced and exported Angolan diamonds, making the diamond industry a vital part of Angola's economy for the first time in the 1930s.[6] Angolans exported 11,839 tons of coffee in 1930, exceeding the previous annual export record of 11,066 tons in 1895.[7] Salazar selected one factory in Angola to produce industrial alcohol in 1932. The factory, competing only with a selected factory in colonial Mozambique, derived its alcohol from molasses and diluted the product with petroleum to maximize its utility.[2] Unfortunately, drought and locusts in 1934 compounded the effects of the Great Depression.[8] Natives, unable to pay the colonists' tax of USD $3.80, faced forced conscription and enslavement. Many farmers, indebted to settlers, auctioned their daughters for sexual slavery. British Consul General Smallbones explicitly labeled and condemned Portugal's conscription policy as slavery in 1930. Portugal's Governor-General for Angola and the minister of colonies denied the charge and Salazar maintained the policy.[9]