Order to soldiers for some blazing coals (4,4)
I believe the answer is:
open fire
I believe this is a double definition.
'order to soldiers' is the first definition.
(instruction to start shooting)
'some blazing coals' is the second definition.
(a fire burning on coal)
'for' is the link.
(Other definitions for open fire that I've seen before include "old-fashioned heater" , "Begin to shoot" , "Domestic hearth" , "army command" , "This may need log on to start" .)