Foul weather, as well as lack of readiness in some of the Austro-Hungarian divisions and in particular of their artillery, delayed the attack for two days but on 24 October there was no wind and the front was misted over. At 02:00, in the northern area of the battle (near
Bovec/Plezzo) 894 metal tubes similar to
Livens Projectors (), dug into a reverse slope, were triggered electrically to simultaneously fire canisters containing of
chlorine–
arsenic agent and
diphosgene, smothering the Italian trenches in a dense cloud of
poison gas. Knowing that their gas masks could protect them only for two hours or less, the defenders fled, but 500–600 were killed. Other parts of the valley were bombed with gas from common grenades. Then the front was quiet until 06:00, when all the Italian wire and trenches to be attacked were bombarded by mortars. At 06:41, 2,200 guns opened fire, many targeting the valley road along which reserves were advancing to plug the gap. At 08:00 two large mines were detonated under strong points on the heights bordering the valley and the infantry attacked. Soon they penetrated the almost undefended Italian fortifications in the valley, breaching the defensive line of the Italian Second Army between the
IV and XXVII Corps. To protect the attackers' flanks, Alpine Troops infiltrated the strong points and batteries along the crests of the adjoining ridges,
Matajur and
Kolovrat, laying out their telephone lines as they advanced to maintain contact with their artillery. The attackers in the valley marched almost unopposed along the excellent road toward Italy; some advanced on the first day. The Italian army beat back the attackers on either side of the sector where the central column attacked, but von Below's successful central penetration threw the entire Italian army into disarray. Forces had to be moved along the Italian front in an attempt to stem von Below's breakout, but this only weakened other points along the line and invited further attacks. At this point, the entire Italian position was threatened. The Italian 2nd Army commander
Luigi Capello was bedridden with fever. Recognizing that his forces were ill-prepared for this attack and were being routed, Capello requested permission to withdraw to the
Tagliamento River.
Cadorna, who believed the Italian force could regroup and hold out, denied the request. Finally, on 30 October 1917, Cadorna ordered the majority of the Italian force to retreat to the other side of the Tagliamento. It took the Italians four full days to cross the river, and by this time the German and Austro-Hungarian armies were on their heels, ambushing the defenders whenever they could. These ambushes would become known as the
Battle of Pozzuolo. Eventually, the retreating Italian soldiers were able to break through the Austro-German encirclement and retreat to the Tagliamento. Then, on 2 November, after an attack by Captain Emil Redl's 4th Battalion of the 4th Bosnian Infantry Regiment, the 55th Infantry Division (Austria-Hungary) established a bridgehead across the Tagliamento River. About this time, however, the rapid success of the attack caught up with them. The German and Austro-Hungarian supply lines were stretched to the breaking point and unable to launch another attack to isolate a part of the Italian army against the Adriatic. Cadorna was able to retreat further and by 10 November had established a position on the
Piave River The Allied
blockade of the German Empire, which the
Kaiserliche Marine had been unable to break, had led to food shortages and widespread malnutrition in Germany and the
Central Powers in general. The inadequate provisioning, as well as the grueling night marches preliminary to the Battle of Caporetto, took a toll on the German and Austro-Hungarian forces. Despite these logistical problems, the initial assault was extremely successful. However, as the area controlled by the combined Central Powers forces expanded, an already limited logistical capacity was overstrained. They had advanced more than in the direction of
Venice, but by the time they reached the
Piave, the soldiers of the Central Powers were running low on supplies and were feeling the effects of exhaustion. As the Italians began to counter the pressure put on them, the German forces lost momentum and were once again caught up in another round of
attrition warfare. ==Aftermath==