'Frechdachs' was a German operation to transfer two large merchant ships, the 6,311-ton Kapitän Diedrichsen (ex-Italian Sebastiano Veniero) and 5,419-ton Città di Tunisi, from the northern part of the Adriatic Sea to the Aegean Sea for use in the transport and then the maintenance of German forces fighting on and later garrisoning several islands in the Aegean sea (29 February 1944).
The operation was schemed in parallel with the postponed 'Freischütz' (iv), which was later cancelled for lack of the naval resources required to support both operations simultaneously. Moreover, the German navy opposed an operation on so large a scale, for the ship concentrations would offer very tempting targets for British air and naval attacks, and efforts to supply substantial garrisons on the islands would be very costly.
Postponement of 'Freischütz' (iv) allowed 'Frechdachs' to start on 29 February, when at 18.00 the convoy left Pola (Pula) with only Kapitän Diedrichsen as Città di Tunisi had to remain in port with engine problems. Unknown to Germans, two large Free French destroyers, Terrible and Malin, had sailed from Manfredonia four hours earlier and shaped course for the south-western part of Dugi island, which they reached at about 20.00 before turning to the north-west and discovering the German convoy on radar a little before 22.00 near Perumda island. With their radar the Free French ships had all the advantages in the following night action, and in just a few minutes left Kapitän Diedrichsen sinking and the corvette UJ 201 (ex-Italian Egeria) sunk by a torpedo.
Only the convoy escorts TA 36 and TA 37 (ex-Italian Stella Polare and Gladio), both badly damaged, managed to return to Pola. The German naval forces in the Adriatic were limited to the use of captured Italian vessels since only smaller vessels could be moved by land and river from Germany, and any loss was therefore irreplaceable.
Further losses eventually forced the Germans to cancel 'Freischütz' (iv).