incendiaries and high explosives to mark the target area. The tactic was expanded into (Blaze Control) with the creation of Brandbombenfelder (Incendiary Fields) to mark targets. These were marked out by parachute flares. Then bombers carrying SC 1000 (), SC 1400 (), and SC 1800 () "Satan" bombs were used to level streets and residential areas. By December, the SC 2500 () "Max" bomb was used. These decisions, apparently taken at the Luftflotte or Fliegerkorps level, meant attacks on individual targets were gradually replaced by what was, for all intents and purposes, an unrestricted area attack or Terrorangriff (Terror Attack). Part of the reason for this was inaccuracy of navigation. The effectiveness of British countermeasures against Knickebein caused the Luftwaffe to prefer fire light instead for target marking and navigation. The shift from precision bombing to area attack is indicated in the tactical methods and weapons dropped. KGr 100 increased its use of incendiaries from 13 to 28 percent. By December, this had increased to 92 percent. Use of incendiaries, which were inherently inaccurate, indicated much less care was taken to avoid civilian property close to industrial sites. Other units ceased using parachute flares and opted for explosive target markers. Captured German aircrews also indicated the homes of industrial workers were deliberately targeted. Final attacks Directive 23: Göring and the Kriegsmarine In 1941, the Luftwaffe shifted strategy again. Erich Raeder—commander-in-chief of the Kriegsmarine—had long argued the Luftwaffe should support the German submarine force (U-Bootwaffe) in the Battle of the Atlantic by attacking shipping in the Atlantic Ocean and attacking British ports. Eventually, he convinced Hitler of the need to attack British port facilities. At Raeder's prompting, Hitler correctly noted that the greatest damage to the British war economy had been done through the destruction of merchant shipping by submarines and air attacks by small numbers of Focke-Wulf Fw 200 naval aircraft and ordered the German air arm to focus its efforts against British convoys. This meant that British coastal centres and shipping at sea west of Ireland were the prime targets. Hitler's interest in this strategy forced Göring and Jeschonnek to review the air war against Britain in January 1941. This led to their agreeing to Hitler's Directive 23, Directions for operations against the British War Economy, which was published on 6 February 1941 and gave aerial interdiction of British imports by sea top priority. This strategy had been recognised