10 June 1944
The general offensive of the Leningrad Front begins on the western Isthmus.
Morning on the western Isthmus begins at 4.58 with even heavier artillery bombardment than on the previous day. Over 3,000 artillery pieces and about 300 aircraft maul the Finnish positions; in key areas over 200 guns are firing for every one kilometer.
IV.AK's positions are bombarded continuously for two and half hours to a depth of 2 kilometers. Huge clouds of smoke and dust are kicked up by the shelling that destroys most fortified positions and communication lines still intact. The men and their weapons are buried as the trenches dug in the sandy soil collapse, and those who are wounded are left behind with no possibility to help them.
At 7.20 infantry and tanks of 30.Ka.AK begin their attack in the Valkeasaari sector. The defending JR 1 has three battalions against 18 Soviet battalions and over 100 tanks. Thirty minutes after the attack had started Lieutenant-Colonel Viljanen messages that the front has collapsed. The men flee in panic and attempts to regroup are difficult since most officers are either dead or wounded. By afternoon, the enemy had made a 20km wide and 15km deep breakthrough in 10th Division's sector.
Marshal Mannerheim orders IV.AK to do a fighting retreat to the Vammelsuu - Taipale line (VT-line) and reinforces it with the 3rd Division and the Cavalry Brigade (Rv.Pr.). Major-General Ruben Lagus' Armoured Division (Ps.D) is also ordered out of reserve and move from Viipuri area to the VT-line.
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Finns shoot down 36 Soviet planes.
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The 3rd Brigade in Salla and the 4th Division in Svir are ordered to move to the Isthmus.
Finnish daily losses: 799