The country faces a shortage of troops in the campaign against Russia's better equipped and larger military
William, the Duke of Cambridge, opened the new NHS Nightingale Hospital at the National Exhibition Centre (NEC) via video link.
The hospital is the second of seven being constructed around England in response to the novel coronavirus outbreak which has killed nearly 13,000 people in Britain so far.
It has a 500-bed capacity, which can be increased to 1,500.
Over 400 civilian contractors, along with military personnel and about 500 clinical staff, were involved in its building.