From November 1940 – February 1941, the Luftwaffe shifted its strategy and attacked other industrial cities. In particular, the West Midlands were targeted. On the night of 13/14 November, 77 He 111s of Kampfgeschwader 26 (26th Bomber Wing, or KG 26) bombed London while 63 from KG 55 hit Birmingham. The next night, a large force hit Coventry. "Pathfinders" from 12 Kampfgruppe 100 (Bomb Group 100 or KGr 100) led 437 bombers from KG 1, KG 3, KG 26, KG 27, KG 55 and Lehrgeschwader 1 (1st Training Wing, or LG 1) which dropped 394 short tons (357 t) of high explosive, 56 short tons (51 t) of incendiaries, and 127 parachute mines. Other sources say 449 bombers and a total of 530 short tons (480 t) of bombs were dropped. The raid against Coventry was particularly devastating, and led to widespread use of the phrase "to conventrate". Over 10,000 incendiaries were dropped. Around 21 factories were seriously damaged in Coventry, and loss of public utilities stopped work at nine others, disrupting industrial output for several months. Only one bomber was lost, to anti-aircraft fire, despite the RAF flying 125 night sorties. No follow up raids were made, as OKL underestimated the British power of recovery (as Bomber Command would do over Germany from 1943–1945). The Germans were surprised by the success of the attack. The concentration had been achieved by accident. The strategic effect of the raid was a brief 20 percent dip in aircraft production.