The Thirty Years War (1618-1648) was a particularly hideous war that involved many countries in continental Europe. Swedes were heavily involved, taking much of Germany, before being beaten back by the Spanish. For long periods they had to survive in forests and to remain mobile. The technique for cutting pine with slits to allow the log to burn as a torch was a very handy way for them to create torches wherever they camped.
Please note, these torches are for outdoor use only and should never be used indoors, As with all open fires, sensible precautions should be taken.