Throughout the past 2000 years humans have witnessed lightning bolts flashing in and around erupted ash plumes.
The earliest known written account of volcanic lightning was from Pliny the Elder, an ill fated resident of Pompeii, he wrote; "there was a most intense darkness rendered more appalling by the fitful gleam of torches at intervals obscured by the transient blaze of lightning."
Vesuvius would also be the sight of of the first volcanic lightning studies conducted by Mr. Palmieri who manned the Vesuvius observatory during the eruptions of 1858,1861, 1868, and 1872. Mt Vesuvius eruptions have been relatively frequent and have always included an array of lightning activity within their plumes and ash clouds.
The most well documented volcanic lightning shows ocurred in the eruptions of 1707, 1872, 1906, and 1944. The 1944 eruption is among the earliest to have its volcanic lightning captured in photographs.
Official Airforce photograph of 1944