1. Land - The Gustav Gun - The Fortress Cracker

The Gustav Gun was the biggest gun ever used in war. The weapon was 50 metres long and fired 4 metre long shells. The shells weighted around 5000 kgs. It took half an hour to reload this monster.

That is an actual tank in the background of the shell.

A tank and a human look like tiny ants before this gigantic gun.
Two types of projectiles were fired using a 3000lb. charge of smokeless powder: a 10,584 lb. high explosive (HE) shell and a 16,540 lb. concrete-piercing projectile. Craters from the HE shells measured 30-ft. wide and 30-ft. deep while the concrete piercing projectile proved capable of penetrating 264-inches. of reinforced concrete before exploding! Maximum range was 23 miles with HE shells and 29 miles with concrete piercing projectiles. Muzzle velocity was approximately 2700 f.p.s.
For all its impressive firepower the Gustav was also a hilariously impractical weapon. Turns out bigger is not always better. (Pun intended! Men around the world can rejoice!)
It required 250 men to assemble it and 2500 to lay tracks so that it could travel.
It was primarily built to destroy The French Maginot line, which was basically a row of huge ass forts armed with big cannons and machine guns. However the Wehrmacht's brilliant blitzkrieg tactics bypassed the fortifications entirely making destruction unnecessary.
It was later used to bombard Russia especially in the siege of the heavily fortified port city of Sevastopol.
Under fire from Gustav and other heavy artillery, Forts Stalin, Lenin and Maxim Gorki crumbled and fell. One round from Gustav destroyed a Russian ammunition dump 100 feet below Severnaya Bay; a near miss capsized a large ship in the harbor. Gustav fired 300 rounds during the siege wearing out the original barrel in the process.
This gun was so badass that it destroyed a large ship by missing its target! However that was the only time it showed up in a major battle. It was later captured by the allies and turned into scrap metal.
2. Nimitz class aircraft carriers - Leviathans of the sea.

Just freaking huge!
Hands down the biggest war machine ever built. At 333 metres and 100,000 tons The Nimitz class supercarriers are floating fortresses which give the US naval superiority over any other force in existence.
Aircraft carriers are an important component of the US forces. The Nimitz class carries almost 90 fixed wing aircraft or helicopters which is a larger airforce to itself than most countries in the world.
Advanced strike aircraft like the F-18 hornets give this war machine a nasty bite. Defense is provided by RIM-7 Sea Sparrow missiles and Phalanx CIWS(close in weapon system) provides missile defense.

F-18 Hornets The Carrier's Sword

CIWS The carrier's shield
The carriers are screened by destroyers and cruisers who act as escorts protecting the carrier from submarines and aircraft. The combined group is called as a Carrier battle group. Carrier battle groups maintain US power throughout the globe, acting as a rapid action force. The Nimitiz will soon be superseded by the Gerald R. Ford class in terms of sheer size and displacement.

3. Air- Fixed Wing Aircraft (Battle aircraft not cargo) -

Tu 160 'Blackjack' - Fast flying Nuclear Bomber
The Tu 160 is the largest fixed wing combat aircraft in the world. Conceived by the Soviet Union as a long range supersonic bomber, The TU 160 is both huge and fast. It flies at 2.3 mach making it one of the fastest bomber aircraft in the world. It also has variable swept wings which can be opened or closed in flight according to the pilot's needs.
Variable swept wings

It is 54 meters long and has a mammoth 56 meter long wingspan when fully spread.
This aircraft primarily uses missiles as its main weapon. It is a standoff weapon platform designed to engage the targets with its missiles from outside the range at which the defenders are likely to engage the target.

Look at the size of that bomb bay!
It can deliver a huge payload of conventional or nuclear standoff missiles and then run away to its bases back home. It was developed during the Cold War as a Counter to the US B1 A Bomber. Russia still maintains 15 of these beasts. They are still some of the best and fastest bombers in the world.
*I am not including the B-36 peacemaker as it was never carried out any real combat operations.
4. German war Zeppelins- Behemoths of the Sky
Imagine that you are sitting comfortably in an armchair, sipping Earl grey from a bone china cup while reading a book in January 1915, in London when you hear a terrifying 'Boom' . You go outside and see a giant airship dropping bombs on your beloved city. You would almost certainly crap your pants and run like hell wondering that in the world that thing was.
Dear Ladies and Gents say Hello to the War Zeppelin.

German War Zeppelin over London during WW1.
German war zeppelins are fascinating weapons of war. They look so graceful and ethereal but don't be deceived by their looks because these airships were one of the most terrifying psychological weapons used by the Germans during ww1.
Psychological weapon?
Yes, The zeppelins were primarily made to be bombers who would lead assaults against English docks. However accuracy was shit in those days as there was no accurate bomb sight and the raids were conducted at night. Hence the raids were shifted to target London to cause maximum terror.

No proper bomb sights meant poor accuracy.
The concept of “strategic bombing" that is, targeted airstrikes on a particular location—didn’t exist before WW1. The advent of aerial warfare changed that, and also robbed the British of the protection afforded by the English Channel. The zeppelin allowed Germany to bring the war to the English homeland.
Zeppelins were in many ways superior to the Fixed wing aircraft of that era. They flew higher and farther and carried a much larger payload. Due to their higher ceiling, British fighter planes were initially unable to engage them.
The poor accuracy of the Zeppelins meant that precision bombing of military targets was impossible. However the Germans using their traditional ingenuity decided to use the airships as terrifying weapons which would wage psychological warfare on the citizens of London. The Germans hoped that Zeppelin raids would cause panic among civilians leading to riots and the collapse of the British government or at the very least the withdrawal of their troops from the Western Front.
The raids on London usually did minimal damage but their psychological effect was truly horrifying. The zeppelins scared the living daylights out of the Londoners. It was the first time ever in the history of warfare, that a major city was being bombed from the air. The public despised the Zeppelins and called them 'baby killers'. However they stood strong with the British government.

They British also used the terror of the Zeppelins as a recruiting tool.

Eventually, the British government began to teach the people ways of protecting themselves from the Zeppelin raids. These greatly reduced their fear factor. These lessons would be invaluable during far more devastating Blitz (Battle of Britain) of WW2.
The British greatly improved their anti aircraft guns and fighter aircraft and by 1917 were able to successful defend England against the raids.
A new incendiary bullet was developed which set fire to the airship. These improved fighter aircraft were very effective against the slow airships and finally brought their reign of terror to an end.
I really loved reading Wilbur Cross's Zeppelins of World War I . If you like Zeppelins, this book is a must read.
5. The Yamato class Battleships- Armoured Titans of the Sea.

The Yamato Class battleships were the flagships of the Japanese combined fleet. At 256 meters and a displacement of over 70,000 tons, these behemoths were the biggest battleships ever made and the pride of the Imperial Japanese navy. Only 3 were built.
The Yamato class had the largest naval artillery guns ever fitted to a warship. They lobbed 18 inch shells over 42 kms. In addition to these huge guns, the Yamato was bristling with smaller anti aircraft guns and light cannons.

The big white shell is the Yamato's 18 inch armor piercing shell
It also had extremely dense armor, designed to face off against several smaller battleships and take massive damage. It was also designed in a peculiar way which optimized survivability while reducing weight.
However in spite of its impressive arsenal and armor it was a technically a WW1 ship in a WW2 environment. Aircraft carriers were the battleship's biggest bane and US aircraft carriers would systematically decimate the Imperial Japanese fleets.
The Yamato only used her great guns once against US ships sinking a Escort carrier and a destroyer. It was sunk by American Carrier aircraft in April 1945. It took 10 torpedoes and 7 bombs before capsizing.
The Yamato holds a lot of significance in Japanese culture. An anime series called Space Battleship Yamato has been made. I would actually recommend you to watch it as it is a lot of fun.

All hail the Space Battleship Yamato!!
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