According to Krellenberg, on 8 Sept. evening 8 R-Boote were operational at Leghorn (and were at first ordered, in the event of an Allied direct threat to the area, to reach Genoa or Toulon with the two minelayers and SG 11). Later, after seeing Kapt.z.S. Engelhardt, Kapt.z.S. Diederichs (Chef of 7. Sicherungsdivision) ordered a picket line made up of 5 R-Boote 5 miles off the harbour during the night, extended to 15 miles offshore at first light on Sept. 9. It is this picket line which probably intercepted the two VAS.
According to "La Marina Italiana dall'8 settembre 1943 alla fine del conflitto" by Adm. di Sq. Giuseppe Fioravanzo, USMM (1962), BRANDENBURG and POMMERN, after the complete German occupation of Leghorn harbour and the seizure of all the Italian ships inside, sailed later in the morning, with Kapt. Diederichs on board the former, to execute orders "Ernte einbringen" and "Achse" (capture of all Italian shipping and disarming of crews). Off Antignano they first met the Italian AMC PIETRO FOSCARI escorting the S/S VALVERDE with a cargo of coal en route from Genoa to Portoferraio. Both ships were attacked and forced ashore near Castiglioncello.
FOSCARI (2x120 mm) was under the command of Cap. Corv. Leonarduzzi. During the fighting, German shore batteries joined, and Rear Adm. Romolo Polacchini, Comandante of Marina Livorno, ordered some Italian coastal batteries to fire on the German ships, an order which later cost him 5 months of prison in German hands.
The two German minelayers, joined by 2 R-Boote, later attacked the Italian Navy ammunition transport BUFFOLUTO, en route from La Spezia toward Portoferraio, which was heavily damaged, forced to surrender and brought into the harbour; then the German ships completed the destruction of FOSCARI and VALVERDE at Castiglioncello.