What is the history of a military drum head service What is it's purpose?

It is a tradition going back for centuries that soldiers in the field, without recourse to their chapels or churches on Sunday, would lay their drums neatly, consecrate them by laying their standards on them, and use them as an altar. This tradition is honoured to this day in drum head services over the world. There is an annual drum head service in Worthing, on Steyne Gardens, on the nearest weekend to Veterans Day (27th June