This first episode, Catastrophe, looks at the fact that between 1914 and 1918, 65 million men took up arms. Ten million were killed and 20 million were emotionally and physically incapacitated. The war ushered in new terminologies, new and massive weapons, and a scale of artillery barrages never before imagined.

This episode looks at trench warfare on the Western Front, which was at stalemate in 1915. Communications proved to be a major drawback for both sides, as messages were sent by runners - who invariably faced death. Two simultaneous battles to push back the Germans were launched at Artois by the French, and by the British at Festubert in May 1915. Both failed and brought the realisation that such massive casualties could not be sustained. With a need for more troops, Lord Kitchener went about a recruitment campaign that amassed some one million volunteers. The new volunteer soldiers lacked the discipline of the regulars, and were regarded with some disdain. At the battle of Loos in 1915 a pattern of trench warfare emerged - artillery barrage followed by troops going over the top, and slaughter.

In the battles of WWI a new theatre of war was to emerge – the sky. This new warfare was to prove just as deadly as the trenches, where pilots flew into battle with as little as five hours flying experience, with an average life expectancy of 11 days in 1914. Initially the aircraft replaced hot air balloons as a reconnaissance device, spying and photographing deep behind enemy lines, but in 1915 aviation pioneer Fokker revolutionised the aircraft as a weapon when he synchronised a machine gun with a propeller – allowing German pilots to annihilate French and British planes.

In this episode we discover that there was only one major clash of fleets in World War 1. Instead, the war at sea was one of blockades and sinkings and a small but feared U-boat. By August 1914 Germany and Britain were building massive and expensive warships - the dreadnoughts. The British controlled the North Sea, and built up supplies by commandeering all goods heading for Germany. Britain's survival depended on keeping her trade routes open, and for this reason Germany declared unrestricted submarine warfare on merchant shipping.

When war broke out in 1914 the Eastern Front campaign moved swiftly. Austrian troops invaded Serbia, and Russia, as Serbia's ally, invaded both Germany and Austria. The Austrians quickly retreated, demoralised by the success of the Russian advance. Yet against the Germans, 50,000 Russians were killed or wounded at the battle of Tannenberg. German Generals Hindenberg and Erich von Ludendorff, spurred on by their easy victories against the Russians, dreamed of an extended German empire to the East.

For the Allies, 1918 proved to be the costliest year of the war. On the Western Front 2 million British and 3 million French were either captured, wounded or killed - over a few miles of French and Belgian mud. On 21 March 1918, General von Ludendorff attacked along a 64-mile front which was to be the greatest attack yet seen in modern industrialised warfare. The Germans advanced 20 miles in 14 days, and von Ludendorff set his sights on Paris and victory. Field Marshall Haig rallied his British troops to fight to the end. Casualties ran at 350 000 for both sides, and the toll taken on von Ludendorff's troops had overstretched his war machine.