Defence Secretary Philip Hammond has told the Commons that the Army "must be a forward-looking, modern fighting machine" as he announced details of restructuring of the armed forces.
In a statement to MPs on the Army 2020 review on 5 July 2012, Mr Hammond revealed that the Army will lose 17 major units as it cuts 20,000 regular soldiers by 2020.
The number of regular soldiers will fall from 102,000 to 82,000, while reservists will double to 30,000.
Mr Hammond said ministers intended a greater integration of regular and reserve components and an increased use of contractors, and that the "reserve will be a vital, integrated component of the army".
He said he could "understand the dismay" at the withdrawal or merger of some historic units with close ties to areas of the UK, but said that withdrawal of a unit did not equal redundancy for its members, many of whom could be redeployed.
"No current regimental names or cap badges" will be withdrawn from the infantry.
Shadow defence secretary Jim Murphy said the announcement came as "new threats are emerging" and Nato in Europe would be required to take on a greater military role as the attention of the US turns towards Asia.
He said the defence secretary was delivering "plans for the smallest army since the Boer War" which was "a completely inadequate response".
There was an angry reaction on the Conservative benches when Mr Murphy described the Argyll and Sutherland Highlanders, who will become a single company to carry out public duties in Scotland, as being "reduced to guarding castles and being the backdrop to Japanese tourists' photographs".
He added that "15,000 brilliant part time reservists cannot fill the gap left by 20,000 regulars" and accused the government of delivering "a less powerful army and a less influential nation".
Mr Hammond alleged that Labour would have had to make cuts in the same position, given the deficit in the Ministry of Defence.
When Liberal Democrat MP Bob Russell, whose constituency includes Colchester Garrison, said the Army would be "half the size it was at the time of the Falklands War", Mr Hammond argued that size comparisons were not relevant as equipment and firepower was more advanced today.
Units have different names in different divisions of the Army for historical reasons. The infantry is divided into regiments composed of batallions; other sections of the Army are structured differently.
Further information on the structure of the Army can be found