Sweeping cuts to the number of troops due to be revealed today point to a fundamental reshaping of Britain's Army.
Although commanders say plans will protect many frontline units, famous regiments will be hit.
The Army is set to announce around 3,000 redundancies this year and the RAF and Royal Navy 1,800 as part of planned cutbacks under the Strategic Defence and Security Review (SDSR).
Overall, 30,000 jobs will go across the three services by the end of the decade.
Each of the three services is supposed to identify which units will be reduced in numbers, with the Army's Parachute Regiment and the Brigade of Gurkhas in focus.
The Gurkhas, 3,500 strong, are vulnerable after a campaign led by actress Joanna Lumley to bring their pay and working conditions in line with that of British soldiers. One of the main changes meant Gurkhas can now serve for 22 years, not the 15 to which they were previously restricted, thus adding to the wage bill.
Final cuts will reduce numbers in the Army to 82,000. A number of historic regiments may be merged and bases more dispersed throughout the country.
A senior officer involved in the SDSR process said: "We have no choice in the current economic circumstances, we have to take our share of pain."