The 300 series, which consisted of 5 infantry battalions, with mobilised reservists for full-time duty, have since 2008 been converted into a new regular border regiment, the Rejimen Sempadan.

With the outbreak of the Second World War, the volunteer units were mobilised and fought alongside the regular British, Indian, and Australian troops in the defence of Malaya and Singapore.

Force 136 of the Special Operations Executive was amongst the British formations that coordinated the Malayan resistance (including the Wataniah movement) against the Japanese.

The group then took several hostages and holed up for four days in Bukit Jenalik, Sauk before finally surrendering to security forces.

[2] The national organization of these reserve regiments are as follows: The 515 Infantry Regiment Askar Wataniah, assigned to and with garrison near the Ministry of Defence Headquarters, serves as the combat and ceremonial reserve of both the 1st Battalions of the RMR and RRR, and thus is equivalent to the London Guards of the British Army.

The Wataniah Artillery Batteries are located in Kota Bharu, Taiping, Melaka, Seremban and Kuala Lumpur.

Squadrons are located in Kuala Terengganu, Kajang, Klang and Penang and are affiliated with the Royal Engineers Regiment.

Askar Wataniah also has 4 medical companies (called Kompeni Ubat AW) based in Kuantan, Kluang, Sungai Petani and Kuching.

The Askar Wataniah Specialist Signals Unit specialises in the maintenance of communication, and its members are drawn from amongst the staff of Telekom Malaysia Berhad.

Askar Wataniah Specialist Engineering Units are based at the Markas Jurutera (SP) (HQ L of C) in Bukit Haigate, Kuala Lumpur and comprises: Pasukan Latihan Pegawai Simpanan (PALAPES) or Reserve Officers Training Units (ROTU) were formed at 13 universities and institutions of higher learning all over Malaysia.

Its main purpose is to train (diploma and first degree) students to become subalterns or young officers to serve as active reservists in the TA 500 series upon their commission.

The ROTC or OTC standards were and are still highly regarded as equivalent to their counterpart at Westpoint or Sandhurst, unlike in Malaysia, the PALAPES standard is yet to be officially recognised as equivalent to the current institutions such Cadet Wings RMC, Airforce College, Naval College, ATMA and now UPNM.

The majority of the recruits had prior experience in the Army and Police Cadets and many were former students of the Maktab Tentera DiRaja (Royal Military College).

There are currently thirteen (13) Malaysian public universities and institutions of higher education (IPTAs) hosting PALAPES units.

The mobilised units before disbanded consisted of five 300 series infantry battalions of the Rejimen Askar Wataniah responsible for protecting the northern border of peninsular Malaysia, the security of East-West Highway, and Key Points Units tasked in protecting the strategic areas of the country.

One Private, Ielias Ibrahim was awarded the medal Panglima Gagah Berani (PGB) for his action in a firefight at Grik, Perak on 15 August 1977.