I’m seeing a lot of conspiracy theorists saying that COVID-19 is a liberal/media hoax. Were there similar theories during the Spanish Flu epidemic, especially since there was a war going on at the time?
I don't know whether this counts as a reliable source that is acceptable for this sub, but the following is a quote from lecture 20 ('Pandemic Influence') in Frank Snowden's OYC course 'Epidemics in Western Society Since 1600'.
"There were rumors that the disease perhaps was an act of bio-terror. There were thoughts that there were mysterious German agents who landed on U-boats and started the epidemic. There were suspicious too that poisonous gases associated with the war effort had escaped and caused the disaster."