1.) The largest ever gun
'Schwerer Gustav' (heavy Gustav). Unlike other types of weapon and warmachine where measurement is a complex thing that can vary on the criteria used, this one is pretty indisputable. Even the shells, pictured here, were 7 tonnes and 800 mm in calibre. Like a few outlandish German designs in WWII, however, this monstrous artillery piece proved impractical in reality. Designed specifically to knock out fortresses on the Maginot line, the gun took too long to prepare to do so - the Wehrmacht's armoured thrust had outflanked the line before the weapon could even be positioned! The gun was deployed and used during the Siege of Sevastopol, were it destroyed a munitions depot under the bedrock of the bay.
2.) The largest ever warship
Nimitz-class aircraft carriers. These nuclear-powered leviathans have an overall length of 333m and a full displacement of over 100,000 tons. Although they will, sooner or later, be eclipsed by the USS Gerald R. Ford class 'supercarriers' currently under construction for the US Navy, the Nimitz carriers have some pretty cool features. Their use of nuclear power for propulsion means that they can technically sortie for 20 years without having to refuel, whilst their aircraft complement is between 85-90 helicopters and fixed-wing types.
3.) The largest ever military aircraft
Blohm & Voss BV 238. Now there have been quite a few enormous bombers built over the years; the B-29 and B-52 being the obvious candidates. There is also a cargo plane that takes the title of largest aircraft ever built - the intimidating Antonov An-225 Mriya. But while the An-225 is capable of transporting military cargo, I felt it was not strictly a military aircraft and so the BV 238 just tips it. The BV 238 was a flying boat of extraordinary dimensions. But only one was ever built, and it suffered a rather ignominious end at the hands of allied fighters, as it was strafed and sunk in September 1944 whilst docked at Schalsee.
4.) The largest ever Armoured fighting vehicle
Panzer VIII Maus. Another German design, weighing 200 metric tonnes(!) and carrying a 128 mm main armament, the ironically titled 'Maus' (mouse) is the heaviest fully-enclosed armoured fighting vehicle ever built. It is interesting to note that, alongside 'Schwerer Gustav' and two more spectacular planned vehicles (look up the Landkreuzer P.1000 'Ratte' and the sci-fi-esque Landreuzer P.1500 'Monster') German engineers often looked to create such massive tools of war. I remember a while back on our Facebook feed that a poster had commented suggesting that all the resources and effort put into researching, designing and developing these extraordinary beasts would have been better spent on creating larger numbers of smaller and more effective weapons of war - fighter aircraft, for example. Here's what the respected Panzer General Heinz Guderian had to say on the 'Maus':
' It was intended to mount a 150 mm gun. The total weight of the tank was supposed to reach 175 tons. It should be considered that after the design changes on Hitler's instructions the tank will weigh 200 tons. The model didn't have a single machine gun for close combat, and for this reason I had to reject it. It had the same design flaw that made the Elefant unsuitable for close combat. In the end, the tank will inevitably have to wage a close combat since it operates in cooperation with the infantry. An intense debate started, and except for me, all of the present found the "Maus" magnificent. It was promising to be exactly that, a "giant".'
5.) The largest ever trebuchet
Warwolf. I have to say I really love the name of this thing! Ancient and mediaeval weapons aren't too well-represented on this list, as in many cases measurement is impossible and dimensions have to be guessed at, or gleaned from secondary source material. But it's fair to say that this must have been one of, if not the, largest trebuchets ever built. It was used at the siege of Stirling castle during the Scottish Wars of Independence, and constructed at the behest of Edward Longshanks. Allegedly, the sight of the engine being constructed was enough to persuade many Scots to surrender - but Edward used it anyway. Its full span is currently estimated to have been 300-400 feet, and it was able to deliver a payload of up to 300 lbs with accuracy. The image depicts a scale model of Warwolf housed at Caerlaverock Castle in Scotland.
Of course, there are too many different types of weapon/vehicle/warmachine to fit on one single list. So I'm going to ask you military history buffs to weigh in with other suggestions. What of the largest submarine, for example. What was the largest sword ever used? Or the largest battleaxe? The longest pike? The highest siege tower?! Get in touch if you know the answers!