Article I love involving unknown World War II battle (5)
I believe the answer is:
anzio
'world war ii battle' is the definition.
(Battle of Anzio, 1944)
'article i love involving unknown' is the wordplay.
'article' becomes 'an' (indefinite article).
'love' becomes 'o' (love means zero in tennis).
'involving' means one lot of letters goes inside another.
'unknown' becomes 'z' (algebra).
'an'+'i'+'o'='anio'
'anio' placed around 'z' is 'ANZIO'.
(Other definitions for anzio that I've seen before include "Italian WW2 beachhead" , "Italian port, site of WWII allied landings" , "WW 2 landing in Italy" , "Italian site of WW2 Allied landing" .)