They've been warned they'll have to make multi-billion pound savings after the next general election.
So they are battling to defend their own budgets ahead of a major strategic defence review planned for next year. The total defence budget faces being slashed by more than £3 billion as departments across Whitehall are forced to make eye-watering cuts.
Army chiefs are openly campaigning for more cash to boost troop numbers. They have told ministers they need the money more than the Navy or RAF.
Last week the head of the army, General Sir Richard Dannatt, warned Britain failed to commit enough troops to secure southern Iraq, allowing Iran-backed terrorists to gain strongholds. The Navy and RAF fear they will suffer major cuts to fund extra troops. The RAF especially fears it will be singled out because it played a smaller role than the other forces in Iraq and Afghanistan.
The RAF and Navy are both mounting separate campaigns to persuade the Ministry of Defence they need the money more than the Army.
All three forces are worried about Tory plans to squeeze defence spending, including in Afghanistan.
A senior military source said: "There is a real battle under way among the three forces to protect their budgets. "It is getting so vicious they are briefing against each other. That could mean they all lose out."

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