This was a German, Finnish and Italian attempt, initially schemed by Kenraaliluutnantii Paavo Talvela while commanding the Finnish VI Corps, to seize from the Soviets the strategically important island of Sukho (Suhosaari in Finnish) off the south shore of Lake Ladoga (22 October 1942).
On this lake the primary Axis naval force was a Finnish-commanded flotilla known as the Laivasto-osasto K (Los.K, or Naval Detachment K). The Finns had operated naval units on Lake Ladoga before World War II as Finland’s territory had included the north-western half of the lake until losing it in the 'Talvisota', and with the start of the 'Jatkosota' in June 1941 they started to re-establish a flotilla as soon as their troops had advanced and retaken the area. The headquarters was formed in Läskelä on 2 August 1941, and by 6 August the Finns had established a force based on some 150 motor boats, two tugs used as minelayers, and four steam ferries. The tugs and ferries were armed with 47-mm guns and machine guns, and the sole unit actually designed for naval use was the wholly obsolete 13-ton motor torpedo boat Sisu. The Finns also established coastal batteries on the shores and islands of Lake Ladoga.
As the Finnish advance continued, the flotilla’s headquarters moved south through a series of recaptured towns along the western shore of Lake Ladoga, eventually reaching Sortavala. The harbour at Lahdenpohja became the flotilla’s primary base.
The Germans and Italians each sent naval units to Lake Ladoga to assist the Finns with the coastal defence of the lake and to support the prosecution of the siege of Leningrad. Los.K came formally into existence as a combined Finnish, German and Italian unit on 17 May 1942 with four Italian MAS boats, four German KM minelayers and Sisu: the German and Italian craft comprised a pair of units under Finnish command. First to arrive was the Italian 12a Squadriglia MAS on 22 June with the torpedo boats MAS-526, MAS-527, MAS-528 and MAS-529. The four German KM-minelayers arrived four days later, but these units suffered from the inexperience of their crews and the unreliability of their engines, so it was 10 August before the German boats were all operational.
Between 13 June and 15 August the strength of the anti-Soviet forces on Lake Ladoga was increased by the arrival of two more German naval contingents, the Luftwaffen-Fährenflotille II and Luftwaffen-Fährenflotille III, which had been created in May 1942 at the Belgian port of Antwerp and redesignated Einsatzstab Fähre Ost for duty on Lake Ladoga. Independent of Los.K but nonetheless maintaining close operational ties with it, the two new units comprised 27 Siebel ferries (seven heavy units each mounting two to four 88-mm [3.465-in] Flak guns, six lighter units mounting smaller-calibre Flak guns, six transport units, six repair units, one hospital unit and one HQ unit) as well as nine I-Transporter or infantry boats each capable of carrying 50 soldiers: four of the these boats were outfitted as minesweepers, three were kept as transports, one was outfitted as a hospital and one as a floating headquarters. In addition, one heavy Sturmboot served as another headquarters unit.
The Siebel ferries were the brainchild of the aircraft designer Fritz Siebel, initially for service in Germany’s 'Seelöwe' invasion of the UK planned for 1940. Each comprised a pair of heavy army bridging pontoons braced together with steel cross-beams and covered by a sturdy wooden deck. The ferries initially had a pair of Ford truck engines, driving standard water propellers, one in the after end of each pontoon, and additional power was provided by three 600-hp (447-kW) aircraft engines mounted on an elevated scaffolding spanning the rear deck: the aircraft engines were later removed as they consumed considerable fuel and required a high degree of skilled maintenance. The Siebel ferries displaced between 140 and 170 tons depending on type, and could travel up to 350 miles (570 km) at 8 kt. With their low freeboard and wide flat deck, they were easily configured for a variety of purposes.
Oberstleutnant Siebel eventually had a total of 30 vessels with 2,400 personnel under his command.
The task entrusted to the Los.K was the harassment of the Soviet lines of communication to Leningrad across the southern part of Lake Ladoga, across which British and US food and munitions were delivered to Leningrad. The unit also attacked Soviet positions and undertook small-scale landing operations against targets on the shores of Lake Ladoga. Smaller Soviet patrol boats and several barges delivering food to besieged Leningrad were attacked and sunk during 1942 and 1943, and the Los.K clashed with the craft of the Soviet Ladoga Flotilla, which operated on the lake between 25 June 1941 and 4 November 1944.
The EFO suffered heavy losses in a failed attempt to take Sukho island, 23 miles (37 km) from the lake’s southern shore and on the main supply route to Leningrad. This German-led 'Brasil' started on 22 October 1942. The landing attempt was driven off and, in a running battle, the flotilla was harassed by Soviet aircraft, torpedo boats and gunboats all the way back to its base on the northern shore of the lake. The German losses included the heavy artillery ferries SF 13 and SF 21, light artillery ferries SF 12 and SF 26, and infantry boat I 6. One of the damaged ferries was soon repaired and taken in Soviet service.