I would say Helicopter changed the way troops are deployed and move throughout the battlefield.

Instead of troops moving to deploy in lines, and "push" there way from one city to the next, troops like in Vietnam, could be flown into the battlefield, and flown out, allowing for quicker, more strike orientated assaults. However this doesn't fully replace marching deployment, as flying over something does not push your front lines, as you can very well fly over enemies. A common problem in Vietnam when Americans would land, fight, possibly win, and fly away.

This did not conquer / push the front lines, and they were hard pressed holding the positions because the only way to get re-enforcments / retreat was by air, and not by simply backing up.

Tons.

The major advancement of post-WWII military technology has been advanced electronics and computer control. Almost every major piece of military equipment in the modern age relies on a computer. And many of those systems are either utterly reliant on computers to operate (such as fighter jets and bombers like the F-16 or B-1B which are dynamically unstable and require computer control to stay in the air) or use computers or advanced electronics to derive their main attributes (such as the accuracy and range of computer controlled cannons on a tank, or the precision of a guided missile).

As a rule the history of military developments post WWII has not been bigger, faster, stronger, it's been more precise, more targeted, smarter. Guided missiles and bombs especially have had a huge impact on all aspects of warfare. In the form of ICBMs and SLBMs they transform nuclear warfare into a potent deterrent weapon instead of an aerial bombing force multiplier. In the form of SAMs, air to air missiles, and MANPADs they dramatically transform the nature and impact of aerial combat. And they dramatically increase the effectiveness of naval vessels against attacking aircraft. In the form of cruise missiles they give naval vessels a dramatic boost in potency with the ability to hit land targets reliably that are hundreds of kilometers inland. In the form of anti-shipping missiles they render battleships, dreadnaughts, and other heavily armored naval vessels obsolete. Overall the nature of naval warfare and of aircraft in relation to naval activities has been utterly transformed. Each individual ship and airplane has the capability to be much more potent as the nature of engagements tends to be one of an exchange of guided missiles rather than an exchange of gun and cannon fire punctuated by occasional bomb and torpedo usage. Indeed, the advent of effective air launched anti-shipping missiles has also rendered the use of torpedo planes and dive bombers obsolete.

Meanwhile, the use of GPS and/or laser designating combined with guided missiles and bombs has dramatically changed the nature of infantry fighting. Today, ground units can make use of supporting fire in the form of guided munitions from airplanes, substantially supplementing the need for nearby artillery placements for such fire, and greatly increasing the effectiveness of it. Additionally, the use of hand held anti-tank weapons and of vehicle mounted guided rockets has changed the equation in terms of the use of armor in infantry warfare. As too has been the advent of cell phone triggered IEDs. A major example of some of these changes was the 1991 Gulf War, where lightly armored American Bradley fighting vehicles engaged heavily armored Iraqi main battle tanks and utterly demolished them through the use of TOW missiles. Without guided missile technology that engagement transforms into a battle between a small, thinly armored APC with a 25mm cannon and a heavily armored tank with a 125mm cannon, with obvious results.

Additionally, electronics advancements have given rise to a networked battlefield, where the norm is constant communication down to every single ground unit. Today it's possible for ground battles to be observed live via remote drone or other aerial assets.

Another major advancement has been helicopters. Helicopters are generally superior for air to ground engagements and have proven their mettle in terms of anti-armor capability and anti-personnel capability through many battles. They are also vastly superior for transporting troops and equipment to and from the battlefield. They've enabled entirely new types of operations where commando units are flown in and out of an engagement that lasts only a few hours or perhaps minutes, such as the assassination of Osama Bin Laden.

Additional advancements include the creation of nuclear powered naval vessels, especially submarines; orbital infrastructure (spy satellites, GPS, communications, etc.); the widespread use of select-fire assault rifles by infantry; and lots of more subtle changes such as materials science improvements.

All in all, the nature of combat has changed significantly on the sea, under it, in the air, and on the ground. Whole categories of weapons systems and traditional tactics have been rendered obsolete ranging from torpedo bombers to gargantuan battleships to "tank destroyer" armored vehicles.

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Also, as an aside, a rather interesting development in military technology has been the "hesco bastion". This is an incredibly simple design, which is essentially the combination of a gabion with a sand bag, on a large scale. It's something that could have been built perhaps hundreds of years ago, and mass produced even as far back as the mid 19th century. They are merely large containers with which to pour dirt, sand, and gravel into in order to make a temporary fortification. They are so useful that they are basically ubiquitous in the construction of bases and fortifications by modern armies, but nobody thought to build such a thing until relatively recently.

I was going to try to cover the entire period you have talked about – time constraints limit this though, so I’ll leave that to others. I will have to talk in rather more of a general fashion, so instead of concentrating on the individual impact of numerous technologies that have been developed since the end of WW2 I will try to discuss this briefly on a more broad level.

A modern trope of military strategists is to talk of a “Revolution in Military Affairs”, a term which has been around since at least the 1980s but relates to an ongoing impact on military affairs of ICT (it is actually more appropriate to talk of an evolution in military affairs, but I digress. If you want to research this, you'll get more google hits for RMA than EMA). The basic tenets of this ‘RMA’ theory suggest that modern ICT has reduced the time required to cycle through, and the efficacy of; the OODA loop (Observe-Orient-Decide-Action). Technologies such as lasers and satellites reduce the gap between each of the stages of the OODA loop, to provide more accurate information in a timely manner. This enables a much more fluid and responsive form of combat than has been historically possible, until the advent of the computer age.

Will add more at home if I have the time, as this is a topic of particular personal interest.

Cheap, reliable missiles.

Anti-ship missiles are extremely cheap, compared to the cost of a modern naval vessel; they also pose a significant threat to surface ships. In 1982 during the Falklands War, Argentina sank the HMS Sheffield, a destroyer in the Royal Navy, using a French antiship missile; British intelligence took active efforts to keep Argentina from acquiring more such missiles. No reliable countermeasure exists for the anti-ship missile, meaning that any naval operations off the coasts of states possessing such weapons will be extremely dicey.

Surface-to-air missiles, as a defense system, when manned by a competent, professional force pose a significant threat to an air force. In 1973 during the Yom Kippur war, Egyptian and Syrian SAMs made life extremely difficult for the Israeli Air Force. Planes are harder to hit than ships, though, just due to the speeds involved.

First off, the National Missile Defense system doesn't work and isn't operational, but since that's within 20 years, I won't comment further on it.

Air power has increased in utility massively. Jets can now strike further and faster than ever before, and carry enormous amounts of precision-guided armaments. For instance, a single A-10 Thunderbolt II (an aircraft designed to support troops on the frontlines) carries 1200 rounds of 30mm cannon ammunition and 16,000 pounds of bombs and missiles. This loadout includes AGM-65 Maverick guided missiles and laser-guided bombs.

Compare that to its namesake, the P-47 Thunderbolt, a WWII aircraft of comparable role. The P-47 carried only .50 calibre machine guns (no cannons, and thus could not hurt tanks with its guns) and 2,500 pounds of bombs.

This means that air power is more important than ever before.

Is this a case of "just" bigger, faster, and stronger? I would argue no. It's a paradigm shift. A modern air force can completely dominate a modern battlefield, defeating a conventional army without any boots on the ground. This has been seen in the First Gulf War, Kosovo, and Libya. This was not possible in WWII.

In a conventional conflict, this allows modern air forces to engage in interdiction missions with unprecedented scale and effectiveness. This is reflected in the 80's and 90's NATO doctrine AirLand Battle, which focuses on maneuver warfare on the ground supported by deep interdiction of enemy reserves by air power.

Like I was saying - that old P-47 couldn't hurt a tank unless it managed to drop a bomb directly on it (not easy!). The modern(ish) A-10 can destroy dozens of armoured vehicles in a single sortie with precision, using standoff weapons like the Maverick or its powerful cannon.

It remains to be seen, but I think that massed armour formations of the Blitzkrieg style would be suicidal in the face of modern air power.

ATGMs are another innovation that took hold since WWII. Infantry can now destroy tanks with impunity from beyond the range of the tank's main gun, making defensive positions much more difficult to dislodge. These have been shown to be a decisive factor in more recent armored conflicts, such as the Yom Kippur war. Prior to the invention of the ATGM, infantry in the open were more or less at the mercy of armoured units. This is no longer the case.

Perhaps the biggest changes have come at sea. WWII saw the decline of the battleship and the rise of the aircraft carrier, but the years after WWII saw the rise of the AShM, and more specifically, the large anti-ship cruise missile.

In an interesting asymmetrical approach, Soviet Cold-War doctrine at sea revolved around finding and destroying the US carrier forces using massive barrages of cruise missiles launched at extreme range from bombers and surface combatants. Advances in radar and missile technology made this possible, and it has totally changed the face of war at sea. It is highly likely that a carrier battlegroup would suffer catastrophic damage in the face of such a barrage, and, while the two doctrines were never tested, I think it highly likely that carriers have had their day in major conventional conflicts, and would prove to be exceptionally vulnerable to this kind of massive cruise missile attack.

Well seeing as you can't effectively protect against nukes. A total war would be over before it started. Also even without the big nukes you have battlefield nukes which could easily destroy large armies (they were even given to cuba during the missile crisiswhichwould have made a ground invasion impossible) However if you ignore nukes then you still have lots of mid range rockets such as the tomahawk missile. Other than that surveillance would be much more complete due to satellites.

One major influence has been the work of John Boyd. He was orginally a Korean war fighter pilot, but went on to single-handly develop the idea of using math to predict the performance of fighter aircraft, his Energy–maneuverability theory, where he was able to predict ahead of time in which areas of combat the Mig-19(IIRC) would have an advantage over US aircraft, and in which areas it would be at a disadvantage. He was later proven correct when a Syrian pilot defected with one. Supposedly, all modern combat aircraft are designed according to the theories he developed. (I say "supposedly" because if someone found something even better, they're keeping it very quiet.)

He also pioneered an advanced theory of the idea of "getting in the other guy's decision loop," which he called OODA loop: Orientation, observation, decision, action.

One of the interesting things about Boyd is that he wasn't considered particularly bright. Supposedly his IQ tested out somewhere around 90. Yet he was able to imagine what might be possible, and even taught himself the calculus he needed to do his calculations of aircraft performance.

I've used a lot of wiki links here because I'm feeling lazy, but Boyd: The Fighter Pilot Who Changed the Art of War is a great source for this and more information about him. Definitely worth reading.