Any one watching the Festival of Remembrance on bbc 1 may have noticed the forming of drums in a stack with two standards draped over them then a Padre concecrating it.
This is called a drum head service.
A Drumhead Service is a church service conducted "in the field" during armed conflict, often near the battlefront. Lacking a church to attend, the military command used its drums, piled neatly and draped with appropriate colours (national or regimental flags, for example) to create an altar. Remembering, in much of the Western World, military chaplains or padres were expected to conduct non-denominational or multi-denominational services to the troops, the drumhead altar was a "generic" altar, suited to its military purpose.