▁more ▁serious ▁and ▁challeng ing ▁music . ▁Moore ▁said ▁they ▁had ▁written ▁material ▁" which ▁had ▁to ▁be ▁executed ▁using ▁a ▁musical ▁voc ab ul ary ▁greater ▁than ▁Peter ▁or ▁I ▁could ▁handle ." ▁This ▁led ▁to ▁S la pp ▁Happy ▁asking ▁Henry ▁Cow ▁to ▁be ▁their ▁backing ▁band ▁on ▁their ▁second ▁album ▁for ▁Virgin . ▁After ▁discuss ions ▁between ▁the ▁two ▁bands , ▁they ▁collabor ated ▁in ▁November ▁ 1 9 7 4 ▁and ▁recorded ▁Des perate ▁Stra ights . ▁" E uropa " ▁and ▁" W ar " ▁were ▁re - record ed , ▁and ▁the ▁album ▁was ▁later ▁released ▁under ▁the ▁name ▁" S la pp ▁Happy / Hen ry ▁Cow ". ▁ ▁The ▁success ▁of ▁this ▁collaboration ▁surprised ▁everyone , ▁considering ▁how ▁dis similar ▁the ▁two ▁bands ▁were . ▁The ▁music ▁often ▁had ▁a ▁Berlin ▁Cab aret ▁feel ▁about ▁it ▁with ▁a ▁taste ▁of ▁avant - gar de ▁jazz . ▁S la pp ▁Happy ▁and ▁Henry ▁Cow ▁decided ▁to ▁merge ▁and ▁returned ▁to ▁the ▁studio ▁in ▁early ▁ 1 9 7 5 ▁to ▁record ▁Henry ▁Cow ' s ▁In ▁Pra ise ▁of ▁Learning . ▁The ▁only ▁real ▁contribution ▁from ▁S la pp ▁Happy ▁( bes ides ▁D ag mar ' s ▁singing ) ▁was ▁the ▁Moore / B leg v ad ▁song ▁" W ar ", ▁which ▁bl ended ▁in ▁well ▁with ▁the ▁album ' s ▁political ▁ag gression . ▁But ▁differences ▁in ▁approach ▁between ▁the ▁two ▁groups ▁had ▁come ▁to ▁a ▁head ▁in ▁April ▁ 1 9 7