Petrov used the operational pause to re-energize the construction of Sevastopol’s three lines of defense, which were directed by General-Major Arkadiy F. Khrenov, one of the Red Army’s top engineers. Khrenov had extensive experience building pre-war fortifications, and had been awarded the Hero of the Soviet Union for figuring out how to break through the Mannerheim Line during the Russo-Finnish War. The initial fortifications were primarily trenches, antitank ditches, and wooden bunkers, but Khrenov improved the quality of Soviet fieldworks by directing more tunneling in rock and using the spoil to build stouter artillery bunkers. Engineer equipment was given high priority in supply runs from Novorossiysk, while Khrenov set the naval workshops in Sevastopol to the large-scale manufacture of wooden antipersonnel mines. Khrenov focused on reinforcing the rear and main lines of defense, rather than the forward lines, which were under direct enemy observation. During the month-long lull, his sappers laid 45,000 more mines, including the buried flamethrowers that the Germans detested, and added 20 miles of barbed-wire obstacles.6
Furthermore, Khrenov was able to tie the defenses of the four sectors together better, which made it more difficult for the Germans to exploit the vulnerable sector boundaries.Of course, it was just as important to ensure that there were enough defenders to man Sevastopol’s three lines of defense, and the Stavka succeeded in directing an increasing amount of replacements to the besieged port. Initially, the North Caucasus Military District was able to send only 3,000 unarmed replacements to Sevastopol on November 18, with rifles to follow later.7
However, on the night of December 7/8, the cruisersThe Stavka also moved to simplify the complicated command structure at Sevastopol, once the first German offensive was defeated. The ineffectual Levchenko, who played no real role in the November fighting, was quietly removed on November 19 and later arrested, being charged with inciting panic because he had planned to evacuate the city.8
Oktyabrsky was confirmed as commander of the SOR, but Petrov remained the predominant figure in the ground defense of the city, while Oktyabrsky focused more on expediting supplies and reinforcements from Novorossiysk. In practice, all command decisions were exercised through the Military Council of the Black Sea Fleet, comprised of Petrov, Oktyabrsky, Morgunov, and Ostryakov.