William Wharton’s novel “Birdy” explores that conflict through the eyes of two boyhood friends who are shattered by war — one physically, the other mentally. The book was adapted into a 1984 film starring Matthew Modine and Nicolas Cage, and into a play by MacArthur Fellow Naomi Wallace, produced at London’s West End in 1997 and off-Broadway in 2003. Now it returns with a newly revised script for a Commonwealth Shakespeare Company production Feb. 27-March 17 at Babson College’s Carling-Sorenson Theater in Wellesley.