Editing Tank (section)

===Offense===

As mentioned in the summary above, one of the if not ''the'' defining attribute of the modern tank is its main gun. A modern (i.e. third gen and up) main battle tank must be able to engage any threat it encounters on the battlefield (and occasionally flying above it), hence the gun itself is a carefully weighed compromise between raw firepower, versatility, and overall mass. Nowadays most tanks sport a gun with a caliber between 100mm and 125mm. The said gun must be capable of firing a wide range of different projectile types: at the bare minimum, it should have ammunition specialized for dealing with hard targets such as opposing tanks, or soft targets such as infantry.

Historically though, this was not always the case. The very first tanks, like the British Mk.IV and the german A7V didn't really have a primary armament but were bristling with guns and machine guns. Initially, side-mounted sponsons were adopted for carrying armament because they could aim downwards into trenches. Obviously, as soon as trenches fell out of favour, so too did sponsons. Additionally, as an enemy tank will never be in said trench, [[Land Raider|mounting an anti-tank weapon in the sponson is utterly retarded.]] 

The first ones to figure out the 'definitive' solution as described above were the French with their Renault FT-17 (pictured above), the very first to adopt a turret for the main armament of the tank. While the FT-17 was plagued by a host of teething problems, its overall design was so efficient and cost-effective that ''absolutely everyone'' jumped upon the bandwagon at the end of WWI, and (almost all) the rest is history. Indeed, at one point all nations toyed with the idea of multi-turreted tanks or ''land battleship'' concept, [[Baneblade|whereby a tank would have multiple turrets each with their own weapon]]. The idea was that the tank could attack in all directions at once, but in practice, this led to horribly oversized monstrosities that were less efficient than simply building more tanks with the same armament, and the smallest bomb from a rickety airplane dropped in terminal velocity would obliterate it and ruin weeks of factory man, hours and materials. The madness then died down and coalesced into two main lines of thought right before WW2: The Americans, British, and French limited the number of guns to two on their heavier tanks, one bigger casemate-mounted howitzer to deal with infantry/pillboxes and one smaller turreted AT gun (see also Char B1, the early Churchills and the M3 Lee). The Germans on their side decided 'fuck it!' and just went for specialized tanks sporting either a small-bore long-barreled AT gun or a broad-bore short-barelled howitzer, and then just had both type collaborate on the battlefield (see early Pz.III and Pz.IV). And this went swimmingly for them, at least until the Russians finally entered the dance in 1941 and deployed the revolutionary T-34, whose 76mm gun demonstrated it was possible to have a tank gun both capable of tackling armour ''and'' blowing stuff up with explosive shells, setting the precedent that stands up to this day.

Once at that point, the overall design was definitively set and guns just got bigger and better from thereon. Starting with the Soviet T-62, they started to go from rifled to smoothbore guns. If you are in any way familiar with the development of gunpowder weapons, this may seem like a baffling decision, but there is a good reason. Anti-tank shot went from a simple lump of steel to sub-calibre munitions like APCR and APDS, as detailed on the [[cannon]] page. These essentially try to be better at penetrating by focusing more energy on a smaller area. A later development was APFSDS, the famous "Silver Bullet" or arrow-like penetrators which turned Saddam's tanks into ooey gooey explody Swiss cheesey. Likewise, they also started using HEAT shells, which are designed to use the power of a focused explosion to bore their way through armour; at one point, they were so effective that tanks were designed specifically around their use. Both of these munitions types actually ''suffered'' from the rotational forces imparted by a rifled barrel. For APCR, APDS, and APFSDS, rifling does not stabilize subcalibre rounds nearly as well; likewise, the shaped charge jet from HEAT shells doesn't hold together as well if it's spinning itself apart. Getting rid of the rifling solved a huge number of other problems: it made it easier to fire missiles out of the guns, and also meant that you could fire higher velocity projectiles without having to reline the bore more frequently. The main exception was HESH, which was essentially a shell full of plastic explosive that flattens itself against targets; upon detonation, it creates a shockwave that is transmitted through the material, causing it to break and shatter if concrete, or to spall off into deadly shrapnel if steel. The spin imparted by rifled barrels helps the explosive pat out more evenly, hence why it is still commonly used by the Brits in their tanks.

During the 1960s, there was an attempt to replace the gun with a missile or gun-missile system which... didn't quite pan out. The main problem is that to accommodate guidance systems, fuel, and all that jazz, missiles are a lot larger than an equivalent tank shell, which strictly limits the amount of ammunition that can be carried. Furthermore, limitations associated with the technology at the time (heavy and fragile hardware, minimum firing ranges) precluded their use on tanks. Future vehicles may carry railguns instead, pending the development of a sufficiently capable, lightweight power system and barrels that don't become slagged after like five shots or so.

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On a sidenote:
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That said, while tanks began to coalesce around the turreted concept many remained turretless and as [[Wikipedia:Sturmgeschütz_III|the German StuG]] proves, were successful weapons in their own right. The lack of a turret does have some advantages thanks to how it lowers overall profile and allow for a larger gun to be mounted than could otherwise be the case. That said, a turret-less tank is only really useful if you don't have the money to make a turreted tank, don't have a bigger tank for your bigger gun, ''and'' will only be fighting on the defensive. The latter is the reason why the only guys ever serious about turretless tanks after WWII were the Swedes with their Stridsvagen 103, and the Germans, with their [[Jaguar Jagdpanzer|Kanonenjagdpanzer 90]]. Even today, many SPG's are still built turretless, however those 'support vehicles' aren't considered proper tanks as they lack both the armor and the tactical flexibilty to act as one.
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In addition to the main gun, you also have the following secondary weapons:

*'''Machine guns:''' They've been around since the beginning, in some cases serving as primary weapons, and they're still around as secondary weapons on most armoured vehicles. They can be mounted pretty much anywhere: on the front of the hull, in its own turret on the hull, in the commander's cupola, on the side of the hull, on the back of the turret, beside the cannon (coaxial), or on top of the turret next to the hatch. The latter two are preferred for modern tanks: the coaxial can easily be used by the loader or gunner without having to change stations, and the top-mounted gun can be aimed pretty much anywhere around the tank, including at aircraft. Either medium/general purpose machine guns or heavy machine guns are preferred for firepower and rate of fire sustainment usually as one GPMG on coaxial and a heavy on pintle (with some taking a GPMG pintle), though it's not unheard of for some crews to slap on a couple extra mgs of any variety including light machine guns/squad automatic weapons. The French take a coaxial HMG and both a GPMG and a HMG on the pintles, while America has two GPMGs (one coaxial one pintle) and two HMGs (both pintle) because Murica.
** '''Crew Weapons''' technically count as well as it's not unheard of for some crews to take potshots with SMGs or Rifles they are issued from the hatches or from purpose built fireports.

* '''Autocannons:''' The next step up from machine guns. Like machine guns, they've also served on primary weapons on more than a few tanks. After the Second World War however, they've tended to be relegated to the status of secondary armament, with potential use against light armoured vehicles and helicopters. Despite their obvious firepower advantages, most tanks don't have them, on account of being rather cumbersome and requiring a separate ammunition supply. The only places where you could feasibly mount them are coaxially alongside the main gun like the French [[AMX-30]]; otherwise, you'd have to create a separate compartment somewhere on the turret or hull, as was done with the experimental MBT-70, which had a retractable cupola for it.

* '''Grenade launchers:''' While tank cannons may fire high explosive shells of greater potency, an automatic grenade launcher has similar flexibility to a machine gun in urban environments, only with more firepower. Another form of grenade launcher is the smoke projector that many tanks incorporate as a defensive measure, but that's for later discussion.

* '''Mortar:''' Like the grenade launcher, a mortar on a tank can be handy for fire support. The Aussies took a page from the Germans' "mad genius" book and mounted a [[awesome|7-rounds 178mm spigot mortar]] on the back of a Matilda II tank, the idea being to give their infantry support tanks some serious close-range firepower for those cases something needed to be softened before an assault. That said, it didn't really take off: there were much more efficient ways of providing fire support separate from a tank, and the only reason it was worth bothering with was because many early-war British tanks of that period (like the Matilda) had extremely poor or even non-existent high-explosive shell capability. Nowadays, the only tank to feature a mortar is the [[Merkava]], which largely serves as a utility weapon for firing special munitions such as smoke or illumination rounds. 

* '''Rockets:''' During the Second World War, a lot of countries experimented with mounting rockets on tanks, ranging from the various German ''Nebelwerfer'' attachments or the Calliope mounted on the American M4 Sherman. Like with the example of the Matilda II above, the point was to provide fire support in anticipation of an assault, or otherwise simply reuse obsolete tanks. They fell by the wayside for similar reasons, or were re-invented as dedicated artillery vehicles (like for instance the [[TOS-1 Buratino]]). 

* '''Guided missiles:''' While attempts to use guided missiles as primary armament in tanks have largely failed to succeed ([[Pereh|with one exception]]), they are still being developed as a special munition designed to be launched out of the main gun. This provides tanks with an option to engage targets that are difficult to hit at distance with their main gun, which can include helicopters. Lighter tanks like the [[M551 Sheridan]] typically use guided missiles to give them an extra anti-armor punch when needed. Similarly, old Soviet tanks like the [[T55AM2]] are upgraded to fire advanced missiles as a way of extracting more usage from obsolete but otherwise functional equipment.