took place from 19 August to 29 September 1939. On 14 September, while sailing around the mouth of St George's Channel, U-28 sank a 5,000 GRT freighter, which was her only success of the patrol. Second patrol U-28s second war patrol took place from 8 November to 12 December 1939. For this effort she was instructed to lay a minefield near the port city of Swansea. En route to Bristol, U-28 sank two ships; the 5,000 GRT Dutch tanker MV Sliedrecht and the 5,100 GRT British freighter SS Royston Grange. U-28 then laid her minefield and returned to port in Germany. While the minefield was not an immediate success, it sank the 9,600 GRT British freighter 60 days after it was laid. Third patrol U-28s third sortie took place from 18 February to 25 March 1940. She was instructed to lay mines off the British Naval Base at Portsmouth. After U-28 laid the minefield, she went on to sink two ships for 11,200 GRT. Fourth patrol U-28s fourth war patrol took place from 8 June to 7 July 1940. She was sent to the Western Approaches and turned in an average performance of sinking three ships totalling 10,300 GRT. The Irish government sought an explanation from Germany for the sinking of the neutral Greek ship Adamandios Georgandis: "the entire cargo of which comprised grain for exclusive consumption in Éire" She was sailing from Rosario (in Argentina) to Cork with a cargo of wheat when she was torpedoed and sunk south-west of Ireland at . Fifth patrol U-28s fifth war patrol took place from 11 August to 17 September 1940 and was one of Kuhnke's most productive. In August, she sank two ships for 5,500 GRT. On 10 September, U-28 found and tracked Convoy OA 210. In the darkness of early morning on 11 September, U-28 attacked the convoy and claimed two large freighters (13,000 GRT each) sunk and caused damage to a 10,000 GRT tanker, bringing Kuhnke's total for the patrol to five ships for 30,000 GRT. However, during the postwar analysis, he was only credited with sinking a 2,000 GRT Dutch freighter and damaging a 4,700 GRT British freighter; which, combined with his earlier sinkings, brought his total to four ships for 9,945 GRT. On his return to Lorient Kuhnke was awarded the Knight's Cross for his work. Sixth patrol U-28s sixth and final war patrol took her from