Men dressed in either theatrical or historical attire riding horses.
Men reenacting the American civil war.
Just because men are dressed in historical attire doesn't mean they are reenacting the American civil war.
exists e1 x1 x2.(a_topic(x1) & all x3.((exists s1 x4 x5.(n_horse(x3) & of(x3,x5) & n_riding(x5) & of(x3,x4) & n_attire(x4) & a_theatrical(s1) & Theme(s1,x3)) | exists s2 x6 x7.(n_horse(x3) & of(x3,x7) & n_riding(x7) & of(x3,x6) & n_attire(x6) & a_historical(s2) & Theme(s2,x3))) -> in(e1,x3)) & Theme(e1,x2) & v_dress(e1) & (x1 = x2) & n_man(x1))
exists e1 s1 s2 x1 x2 x3.(n_war(x3) & a_civil(s2) & Theme(s2,x3) & a_american(s1) & Theme(s1,x3) & a_topic(x1) & Theme(e1,x3) & Actor(e1,x2) & v_reenact(e1) & (x1 = x2) & n_man(x1))