South Africa 1941 cover to a serviceman in Durban, later in East Africa, redirected & returned

Cover only; empty envelope, no letter.

Postal marks :
CAPE TOWN 3 IV 41, c.d.s. on stamp

A.P.O. - U - M.P.K  7  30 MAY 41, c.d.s., redirection,  on front 

E.A.  A.P.O. 51 , date unreadable forwarding mark , on front

E.A..A.P.O. 2  1 VIII 41, c.d.s., transit / arrival on reverse

RETURNED LETTER OFFICE CAPE TOWN  3 IX 41 c.d.s. .on reverse

Instruction h/s front& back:
PRESENTADDRESS UNKLNOWN.
SENDER PLEASE FURNISH
NEW ADDRESS
__________________
Condition:
=================
fair / good

age tone and soiling
opened roughly at right