View source for A13 Mk I (3rd R.T.R.)

{{About
| about = British light tank '''{{PAGENAME}}'''
| usage = other versions
| link = A13 (Family)
}}
{{Specs-Card
|code=uk_a_13_mk1_3rd_rtr
|images={{Specs-Card-Image|GarageImage_{{PAGENAME}}.jpg}}
}}

== Description ==
<!-- ''In the description, the first part should be about the history of the creation and combat usage of the vehicle, as well as its key features. In the second part, tell the reader about the ground vehicle in the game. Insert a screenshot of the vehicle, so that if the novice player does not remember the vehicle by name, he will immediately understand what kind of vehicle the article is talking about.'' -->
The '''{{Specs|name}}''', also designated in-game as the '''{{PAGENAME}}''', is a premium rank {{Specs|rank}} British light tank {{Battle-rating}}. It was introduced along with the initial British tree line in [[Update 1.55 "Royal Armour"]] and was the prize in the [[wt:en/news/3477--en|2015 "Christmas gift"]] giveaway. At some point, it was given for free if you chose Britain as your first nation when you started the game.

== General info ==
=== Survivability and armour ===
{{Specs-Tank-Armour}}
<!-- ''Describe armour protection. Note the most well protected and key weak areas. Appreciate the layout of modules as well as the number and location of crew members. Is the level of armour protection sufficient, is the placement of modules helpful for survival in combat? If necessary use a visual template to indicate the most secure and weak zones of the armour.'' -->
'''Armour type:'''

* Rolled homogeneous armour (hull, turret)
* Cast homogeneous armour (Gun mantlet)

{| class="wikitable"
|-
! Armour !! Front (Slope angle) !! Sides !! Rear !! Roof
|-
| Hull || 14 mm ''Front plate'' <br> 14 mm (0-62°) ''Front glacis'' <br> 14 mm (64°) ''Lower glacis'' || 7 + 7 mm || 14 mm (0-62°) || 14 mm
|-
| Turret || 14 mm (0-15°) ''Turret front'' <br> 14 mm (1-63°) ''Gun mantlet'' || 14 mm (21°) || 14 mm (2°) || 14 mm
|-
| Cupola || 14 mm || 14 mm || 14 mm || 14 mm
|-
|}

'''Notes:'''

* Suspension wheels and tracks are 15 mm thick while the torsion bars in between the side armour are 10 mm thick.
* Hoisting points and optics covers are 14mm thick.
* The sides of the hull benefit from spaced armour (2 x 7 mm spaced ~10 cm apart) but the thickness of the plates is too poor to properly act as such: HEAT and HE shells have no problem defeating it.
* 2 smoke launchers are installed on the right side of the turret. Smoke grenades can be launched individually in the direction the gun is pointing at, 50 m away from your tank. The reload sequence takes places once both launchers are empty.
* The {{PAGENAME}} is among the least armoured tanks in the game. Be aware that even when angling, most enemies can reliably penetrate you from 1,000 m distance.
* Even when only exposing the turret of your tank to shoot at an enemy, you can receive devastating damage as your thinly armoured turret is pretty wide and contains 3 crew members out of 4.

=== Mobility ===
{{Specs-Tank-Mobility}}
<!-- ''Write about the mobility of the ground vehicle. Estimate the specific power and manoeuvrability, as well as the maximum speed forwards and backwards.'' -->

{{tankMobility|abMinHp=527|rbMinHp=301}}

The acceleration is good and the top speed is in line with light tanks at the same BR. The reverse speed is slow and won't let you overextend. The tracks are narrow, which gives the {{PAGENAME}} poor handling on soft terrain (snow, mud, sand). The tracks are also long, which causes the tank to understeer and lose a lot of speed when turning. All this combined with the lack of neutral steering makes turning on the spot slow.

=== Modifications and economy ===
{{Specs-Economy}}

== Armaments ==
{{Specs-Tank-Armaments}}
=== Main armament ===
{{Specs-Tank-Weapon|1}}
<!-- ''Give the reader information about the characteristics of the main gun. Assess its effectiveness in a battle based on the reloading speed, ballistics and the power of shells. Do not forget about the flexibility of the fire, that is how quickly the cannon can be aimed at the target, open fire on it and aim at another enemy. Add a link to the main article on the gun: <code><nowiki>{{main|Name of the weapon}}</nowiki></code>. Describe in general terms the ammunition available for the main gun. Give advice on how to use them and how to fill the ammunition storage.'' -->
{{main|QF 2-pounder (40 mm)}}

The cannon loses accuracy and penetration power quickly over distance. The accuracy loss is noticeable as soon as 500 m distance and becomes a handicap over 700 m. Penetration at close range is good but becomes ineffective at 500 m and beyond. The high muzzle velocity allows for rather flat trajectories but targeting enemies at long range will be hindered by the loss of accuracy.

Vertical stabilizer (shoulder stop) allows you to fire when moving at slow pace (a few km/h). The turret traverse speed is average but rather slow when compared than other tanks at the same BR. The depression angle is very important and allows you to shoot easily from behind a ridge. Recoil is barely noticeable. The reload time is very short, allowing you to shower your enemies with a continuous rain of shells. Targeting procedure is quick and simple.

{| class="wikitable" style="text-align:center" width="100%"
|-
! colspan="5" | [[QF 2-pounder (40 mm)|40 mm QF 2-pounder]] || colspan="5" | Turret rotation speed (°/s) || colspan="4" | Reloading rate (seconds)
|-
! Mode !! Capacity !! Vertical !! Horizontal !! Stabilizer
! Stock !! Upgraded !! Full !! Expert !! Aced
! Stock !! Full !! Expert !! Aced
|-
! ''Arcade''
| rowspan="2" | 87 || rowspan="2" | -15°/+20° || rowspan="2" | ±180° || rowspan="2" | Vertical || 15.23 || 21.08 || 25.60 || 28.31 || 30.12 || rowspan="2" | 3.64 || rowspan="2" | 3.22 || rowspan="2" | 2.97 || rowspan="2" | 2.80
|-
! ''Realistic''
| 9.52 || 11.20 || 13.60 || 15.04 || 16.00
|-
|}

==== Ammunition ====
The available choice of ammunition focuses on armoured targets:

* '''Shot Mk.1 AP/T	''': AP; a solid shot with no explosive filler offering a good penetration power until 500 m.
* '''Shot Mk.1 APHV/T''': AP; the same projectile but with higher muzzle velocity, offering a good penetration power until 1,000 m.
* '''Shot Mk.IXB APCBC/T''': APCBC; a solid shot with a ballistic cap and no explosive filler, offering the best penetration power from 0 to 500 m for the {{PAGENAME}}.
* '''Shell Mk.1 AP/T''': APHE; an armour-piercing shell with explosive filler that will one-shot any tank that is penetrates but has an average penetration power. Use it preferably when enemies are at close range.

Projectiles without explosive filler will most of the time incapacitate enemy tanks and require a second shot to properly knock them out. Knowledge of the positions of crew members in the targeted tank is crucial when playing with solid shots.

{| class="wikitable sortable" style="text-align:center" width="100%"
! colspan="8" | Penetration statistics
|-
! rowspan="2" data-sort-type="text" | Ammunition
! rowspan="2" | Type of<br>warhead
! colspan="6" | '''Penetration @ 0° Angle of Attack (mm)'''
|-
! 10 m !! 100 m !! 500 m !! 1,000 m !! 1,500 m !! 2,000 m
|-
| Shot Mk.1 AP/T || AP || 72 || 68 || 52 || 37 || 27 || 19
|-
| Shot Mk.IXB APCBC/T || APCBC || 89 || 86 || 77 || 66 || 57 || 50
|-
| Shot Mk.1 APHV/T || AP || 80 || 75 || 58 || 41 || 30 || 21
|-
| Shell Mk.1 AP/T || APHE || 66 || 62 || 49 || 36 || 26 || 20
|-
|}
{| class="wikitable sortable" style="text-align:center" width="100%"
! colspan="10" | Shell details
|-
! rowspan="2" data-sort-type="text" | Ammunition
! rowspan="2" | Type of<br>warhead
! rowspan="2" | Velocity<br>(m/s)
! rowspan="2" | Projectile<br>Mass (kg)
! rowspan="2" | Fuse delay<br>(m)
! rowspan="2" | Fuse sensitivity<br>(mm)
! rowspan="2" | Explosive Mass<br>(TNT equivalent) (g)
! colspan="3" | Ricochet
|-
! 0% !! 50% !! 100%
|-
| Shot Mk.1 AP/T || AP || 792 || 1.08 || N/A || N/A || N/A || 47° || 60° || 65°
|-
| Shot Mk.IXB APCBC/T || APCBC || 792 || 1.24 || N/A || N/A || N/A || 48° || 63° || 71°
|-
| Shot Mk.1 APHV/T || AP || 853 || 1.08 || N/A || N/A || N/A || 47° || 60° || 65°
|-
| Shell Mk.1 AP/T || APHE || 792 || 1.08 || 1.2 || 9 || 20.9 || 47° || 60° || 65°
|-
|}

==== [[Ammo racks]] ====
<!-- '''Last updated: 1.99.0.51''' -->
{| class="wikitable" style="text-align:center"
|-
! Full<br>ammo
! 1st<br>rack empty
! 2nd<br>rack empty
! 3rd<br>rack empty
! 4th<br>rack empty
! 5th<br>rack empty
! 6th<br>rack empty
! 7th<br>rack empty
! 8th<br>rack empty
! 9th<br>rack empty
! 10th<br>rack empty
! 11th<br>rack empty
! 12th<br>rack empty
! 13th<br>rack empty
! 14th<br>rack empty
! 15th<br>rack empty
! 16th<br>rack empty
! Visual<br>discrepancy
|-
| '''87''' || 78&nbsp;''(+9)'' || 75&nbsp;''(+12)'' || 72&nbsp;''(+15)'' || 69&nbsp;''(+18)'' || 66&nbsp;''(+21)'' || 62&nbsp;''(+25)'' || 60&nbsp;''(+27)'' || 56&nbsp;''(+31)'' || 51&nbsp;''(+36)'' || 47&nbsp;''(+40)'' || 43&nbsp;''(+44)'' || 41&nbsp;''(+46)'' || 36&nbsp;''(+51)'' || 31&nbsp;''(+56)'' || 16&nbsp;''(+71)'' || 1&nbsp;''(+86)'' || style="text-align:left" | No
|-
|}
[[File:Ammoracks_A13MkI.png|right|thumb|x250px|[[Ammo racks]] of the {{PAGENAME}}]]

Notes:

* To minimize the risk of ammo rack detonation, keep racks 1 to 14 empty (31&nbsp;''(+56)''). This will guarantee the center hull is empty of shells.

=== Machine guns ===
{{Specs-Tank-Weapon|2}}
<!-- ''Offensive and anti-aircraft machine guns not only allow you to fight some aircraft but also are effective against lightly armoured vehicles. Evaluate machine guns and give recommendations on its use.'' -->
{{main|Vickers (7.7 mm)}}

The rate of fire of the 7.7 mm Vickers is slow compared to other MGs at the same BR. The small calibre will only allow you to use it as a spotting gun or to mow down minor obstacles blocking your line of sight. Except for engaging vehicles with crew members in the open, your MG won't deal much damage to enemies.

{| class="wikitable" style="text-align:center" width="50%"
|-
! colspan="5" | [[Vickers (7.7 mm)|7.7 mm Vickers]]
|-
! Mount !! Capacity (Belt) !! Fire rate !! Vertical !! Horizontal
|-
| Coaxial || 3,500 (250) || 390 || N/A || N/A
|-
|}

== Usage in battles ==
<!-- ''Describe the tactics of playing in the vehicle, the features of using vehicles in the team and advice on tactics. Refrain from creating a "guide" - do not impose a single point of view but instead give the reader food for thought. Describe the most dangerous enemies and give recommendations on fighting them. If necessary, note the specifics of the game in different modes (AB, RB, SB).'' -->
This vehicle's role is that of a light tank in the truest sense, sporting an acceptable gun, great mobility and virtually no armour to speak of.

This tank has a very active playstyle and should not be used in the front lines. Instead, use your mobility to your advantage: Spot, flank and provide artillery support for your teammates, blind your enemies with well-placed smokes screens in key avenues. Make sure to only target secluded enemies in flanking tactics so you can take full advantage of the element of surprise and outflank your opponent. Never expose yourself for too long because even anti-aircraft guns are a potential threat to your non-angled armour. The [[Ordnance QF 2-pounder (40 mm)|QF 2-pounder]] has an awfully long-range accuracy so you must get close to your enemies to actually land a shot where you expect. Load up this agile (but reluctant) cat with ammo and flank your enemies with a constant flow of bullets.

=== Pros and cons ===
<!-- ''Summarise and briefly evaluate the vehicle in terms of its characteristics and combat effectiveness. Mark its pros and cons in a bulleted list. Try not to use more than 6 points for each of the characteristics. Avoid using categorical definitions such as "bad", "good" and the like - use substitutions with softer forms such as "inadequate" and "effective".'' -->

'''Pros:'''

* Good gun for its rank with fast reload
* High top speed and good HP/ton ratio
* Slim target, is hard to get spotted and shot at
* Has a shoulder stabiliser, an advantage in CQC
* Brings lots of ammo to the fight (87 rounds max)
* Has forward-launching smoke launchers
* Decent turret sewing rate
* -15° gun depression ensures great terrain adaptation
* Four crewmen and a three-man turret increases survivability
* Very effective in its historical role, a flanker and scout

'''Cons:'''

* Next to no armour, can be frontally penetrated by HMG
* Loses speed when turning
* Wiggles when trying to turn on 5th gear
* Very slow reverse speed, might get the player destroyed
* The coaxial Vickers MG has an incredibly slow fire rate, hard to finish off fast targets like [[AS 42]]
* Not effective at anything other than how it was historically used; ill-advised to brawl or support heavier vehicles

== History ==
<!-- ''Describe the history of the creation and combat usage of the vehicle in more detail than in the introduction. If the historical reference turns out to be too long, take it to a separate article, taking a link to the article about the vehicle and adding a block "/History" (example: <nowiki>https://wiki.warthunder.com/(Vehicle-name)/History</nowiki>) and add a link to it here using the <code>main</code> template. Be sure to reference text and sources by using <code><nowiki><ref></ref></nowiki></code>, as well as adding them at the end of the article with <code><nowiki><references /></nowiki></code>. This section may also include the vehicle's dev blog entry (if applicable) and the in-game encyclopedia description (under <code><nowiki>=== In-game description ===</nowiki></code>, also if applicable).'' -->

===Development===
The British development on their cruiser tanks, tanks that focus on mobility to exploit breakthroughs beyond enemy lines, took a turn in 1936 after General Giffard LeQuesne Martel became the Assistant Director of Mechanization at the British War Office, the head of the army in the government. Martel, an advocate of the tanks, and developer of the concept of "tankettes", witnessed a tank demonstration in 1936 that had Soviet designs. The one that attracted his attention was the [[BT-5|BT light tank]]. The BT's use of the Christie suspension had Martel argue for the usage of the same suspension in their tank designs, to which the British government complied with the purchase and licensing of the system from the Nuffield Organization.

The acquired vehicle from the purchase of the Christie suspension was labelled as the ''A13E1'' and became part of the design development under the designation ''Cruiser Mk III (A13)''. The General Staff requested for the vehicle to have 30 mm of armour, a 2-pounder gun, and a road speed of 48 km/h. The original vehicle was extensively reworked due to many interior and mechanical issues. Until the tank design was finished, the British Army adopted the ''Cruiser Mk I (A9)'' tank for use, but these tanks were delayed due to the A13's near completion. The first prototype was delivered in 1937 under the name ''A13E2'', this featured the turret from the A9 cruiser tank, with a 2-pounder and a Vickers machine gun. The armour on the prototype was 15 mm and the design could reach a top speed under a governor of 48 km/h (64 km/h ungoverned). The last and revised design was the ''A13E3'' that became adopted by the British Army and ordered into production in 1939. The General Staff specification number for the tank was the '''A13 Mk. I, Cruiser Tank Mark III'''. 65 of these tanks were ordered from the Nuffield Mechanization & Aero Limited, to which 30 were built before the War Office decided to upgrade the A13 Mk.I with more armour than the '' [[A13 Mk II|A13 Mk.II, Cruiser Tank Mk IV]]''. Some of the A13 Mk.I Cruiser Mk III was also converted into Mk IV to stay modernized.

===Combat usage===
The A13 first saw combat in the Battle of France under the British Expeditionary Force in 1940. The A13 encountered many troubles during its employment, the crew having little to no training with the new tanks due to their rushed adoption into service. The tanks were in poor condition and some were even missing parts. The A13s were used in the 1st Armoured Division, but many were either destroyed by the superior German armoured forces or abandoned at Calais during the evacuation of Allied troops at Dunkirk, which forced the units to leave behind their heavier equipment.

After the disaster at France, the A13 were still used to support the war. Some were sent to Greece to support their defence against Germany in the Battle of Greece, but a majority were sent to North Africa as part of the Western Desert Campaign near Libya under the 7th Armoured Division. Compared to the time in France, the A13s in North Africa fared much better, ironing out most of its initial defects, and was even more suited to the environment than other tank designs. The A13 was popular with the crew for its high speed, reliability, and a powerful 2-pounder cannon that could engage a majority of Axis tanks in 1941. However, there was an insufficient number of A13s available for use, so tank units were mixed with the faster cruiser tanks and slower infantry tanks, which caused tactical and logistical difficulties trying to accommodate all of the tanks. Another deficiency with the tank and every other British tank with the 2-pounder was the lack of high-explosive shell issued to the tankers, which made them vulnerable to anti-tank guns, which caused a majority of British tank losses in the North African Campaign. Still, the A13 fared very well with its armour and armament until late 1941 where better armoured [[Pz.III L|Panzer IIIs]] and [[Pz.IV G|Panzer IVs]] began to appear on the battlefield.

Due to its growing obsolescence on the battlefield, the A13 was replaced in 1941 by the better armoured [[Crusader Mk II|A15 Crusader tank]].

== Media ==
<!-- ''Excellent additions to the article would be video guides, screenshots from the game, and photos.'' -->

;Skins

* [https://live.warthunder.com/feed/camouflages/?vehicle=uk_a_13_mk1_3rd_rtr Skins and camouflages for the {{PAGENAME}} from live.warthunder.com.]

;Videos
{{Youtube-gallery|tp7_VTC3FoE|'''{{PAGENAME}} Review. A careful playstyle is needed''' - ''Joseph 2000''|4_cJ1CpEatw|'''Best gun depression'''  discusses the {{PAGENAME}} at 1:33 - ''War Thunder Official Channel''|tx2MxpbY0b4|'''{{PAGENAME}} Tank Review''' - ''NUSensei''}}

== See also ==
<!-- ''Links to the articles on the War Thunder Wiki that you think will be useful for the reader, for example:''
* ''reference to the series of the vehicles;''
* ''links to approximate analogues of other nations and research trees.'' -->

;Other vehicles of similar role or configuration
* [[M2A4]]
* [[M3 Stuart]]
* [[Pz.35(t)]]
* [[Stuart I]]

== External links ==
<!-- ''Paste links to sources and external resources, such as:''
* ''topic on the official game forum;''
* ''other literature.'' -->

* [[wt:en/news/3477--en|[Special] Collect a famous А13 Mk I 3rd RTR for Christmas!]]
* [[wikipedia:Cruiser_Mk_III|[Wikipedia] Cruiser Mk III]]
* [https://tanks-encyclopedia.com/ww2/gb/A13_Cruiser_MkIII.php <nowiki>[Tanks Encyclopedia]</nowiki> Cruiser Mk.III, A13]
* [[wikipedia:3rd_Royal_Tank_Regiment|[Wikipedia] 3rd Royal Tank Regiment]]

{{Britain light tanks}}
{{Britain premium ground vehicles}}