'Wasserschlauch' was a German and Croat undertaking to advance into Gorski Kotar in occupied Yugoslavia (23/27 August 1944).
After the Germans had failed in their first attempt to advance from Ogulin into Gorski Kotar on 1/4 August 1944, the partisan forces of Marshal Josip Broz Tito committed their 13th Division in an unsuccessful attack on the German garrison of Dreznica. With the concentration of the 13th Division known, the Germans could easily plan another attempt to advance into Gorski Kotar using the 392nd Aufklärungsabteilung of Generalleutnant Johann Mickl’s 392nd Division (kroatische) supported by the 33rd Ustase Battalion and Četniks of the Generalski Stol garrison. The redeployment of the same division’s 3/846th Grenadierregiment to Kraljevica on the Adriatic coast was a secondary objective.
The 'Wasserschlauch' advance began on 23 August on the axes from Bosanci to Severin na Kupi and from Ogulin to Vrbovsko. During the afternoon of the following day, after the Germans had surprised the staff of the 13th Division in Brod Moravice and the staff of the XI Corps in the village of Kuti, the division’s 2nd Brigade was moved to block this advance. On 27 August operation was over and by 28 August all Axis formation have withdrawn from Gorski Kotar back to their garrisons.
During the operation the Germans claimed to have killed 96 partisans (the latter admitting to only 19 dead including a brigade commander), wounded 26 and captured 21. To hold the divisional supply base in Josipdol, the Germans shifted a field replacement battalion from Dreznica to Josipdol, which allowed the partisans to move into Dreznica and, using units formed from staff, supply and artillery personnel, cut the supply route between the Kapela pass and Zute Lokve.