Reservists will get £40 million of new kit and extra overseas training opportunities in the latest steps to increase the size of the part-time forces.
Members of the Territorial Army - to be renamed the Army Reserve under the shake-up - will be able to use high-tech equipment including helmet-mounted night vision and upgraded SA80 rifles.
A white paper on Wednesday will set out financial incentives for small firms employing reservists.
It will set out how the number of trained reservists will increase from 19,000 to 30,000 by 2018 in preparation for them taking on more operations alongside their Regular counterparts.
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Five people were killed and dozens more were injured after a car and knife attack in the capital on Wednesday afternoon.
Among those expected to attend the ceremony will be former US President Bill Clinton and ex-Northern Ireland first minister Peter Robinson.
Five people have been killed and 40 injured after a car and knife attack in London on Wednesday.