Serbia and Montenegro: Guerrilla risings begin against weakened Austrian garrisons, continue for duration of war.
Battle of the Somme: British storm Horseshoe Trench. Germans massing in Mametz Wood. Germans recapture Estrees south of Somme. French Foreign Legion (869 casualties) relieved after sending back 730 PoWs and 4 MGs and repulsing 2 night counter-attacks.
North Sea: U-boat campaign against fishing vessels begins (36 sunk).
Eastern Mediterranean: U39 sails, lands Lieutenant Todenwarth and 7 men with munitions for Senussi, North Africa (fetched back October 13).