Despite the initial weakness of its armed forces, Great Britain declared a naval blockade of Germany on September 3, two days after the latter invaded Poland. The Royal Air Force dropped 6 million leaflets on towns in northern Germany and the Ruhr district, the first of the propaganda raids. 
 Germany countered with a naval blockade of its own against Britain on September 11, stating that since economic warfare had been forced on it, it could not but repay in the same coin.