▁fee , ▁known ▁as ▁ad oh ament um ▁or ▁ad oh a . ▁Most ▁bar ons ▁and ▁counts ▁preferred ▁to ▁pay ▁the ▁fee ▁which ▁thus ▁developed ▁into ▁a ▁tax ▁already ▁under ▁the ▁Norman ▁k ings ▁of ▁Sic ily . ▁The ▁land own ers ▁collected ▁the ▁fee ▁from ▁their ▁ten ants , ▁thus ▁in ▁practice ▁the ▁pe as ants ▁were ▁to ▁pay ▁the ▁ad oh a . ▁Those ▁who ▁lived ▁in ▁the ▁royal ▁dem es ne all ▁burg h ers ▁and ▁the ▁majority ▁of ▁the ▁pe asant ry w ere ▁subject ed ▁to ▁lev ies ▁in ▁money ▁or ▁in ▁kind , ▁known ▁as ▁collect a . ▁The ▁monarch s ▁could ▁in ▁theory ▁freely ▁demand ▁such ▁lev ies , ▁only ▁their ▁fear ▁of ▁ri ots ▁limited ▁their ▁gre ed . ▁ ▁The ▁Holy ▁Roman ▁Emperor , ▁Frederick ▁II , ▁who ▁was ▁also ▁king ▁of ▁Sic ily , ▁sum mon ed ▁the ▁host ▁in ▁each ▁year ▁after ▁ 1 2 3 1 . ▁This ▁practice ▁enabled ▁him ▁to ▁ann ually ▁collect ▁the ▁ad oh a , ▁transform ing ▁it ▁into ▁a ▁regular ▁tax . ▁The ▁ad oh a ▁and ▁the ▁collect a ▁were ▁not ▁differenti ated ▁from ▁ 1 2 3 8 ▁and ▁they ▁were ▁un ited ▁three ▁years ▁later . ▁ ▁References ▁ ▁S ources ▁▁▁▁▁▁ ▁Category : K ing dom ▁of ▁Sic ily ▁Category : E conom ic ▁history ▁of ▁Italy <0x0A> </s> ▁Robert ▁Gil m our ▁may ▁refer ▁to : ▁ ▁Sir ▁Robert ▁Gil m our , ▁ 1 st ▁Baron et ▁(