World War I forced the industry to seek new sources of energy and to install large distribution networks. Amid huge instability, US power companies began to join forces, attempting to become strong enough to withstand the economic and financial uncertainty. However, no one foresaw the magnitude of the stock market crash of 1929, which brought these emerging groups to the verge of ruin. In Spain, which had experienced a period of economic growth at the start of the 20th century, the industry suffered a severe setback in 1936 whose impact would be felt for the following two decades: the Civil War abruptly halted development, destroyed facilities and made maintaining the little equipment that remained extremely difficult.