It is a bright, cold day in April, and while the clocks aren’t actually striking 13, it feels as if they might at any moment. Almost a century after the outbreak of the first world war (on July 28, 1914), Flanders – where hundreds of thousands fought and died – still retains a faint air of Armageddon.

Travellers normally head to Belgium to get a taste of its legendary chips, chocolate and alcohol, or to take in its architecture and diverse cultures. A battlefield tour provides a different perspective and, of course, there’s no prohibition on a few Hoegaardens and a plate or two of French frites or Flemish frietjes at lunch or dinner, plus a handful of Leonidas afterwards.

Besides, the tour lasts just four days, so heading on to Antwerp or Bruges is perfectly feasible.

The tour centres on Ypres – Ieper in Flemish, “Wipers” to thousands of foreign troops who fought here – a manufacturing hub dating from the Middle Ages that was obliterated in five battles.

“If the German armies had got past Ypres, they’d have got to the Channel ports and the war would have been over,” says Marc Le Fleming, an unconventional Anglo-Dutch historian whose Belgian battlefield tours take in Waterloo and the Ardennes as well as first world war sites.

“The British alone suffered 56,000 casualties at Ypres in the autumn of 1914, which annihilated what had been the regular army. This was the start of a total war, and the world has never been the same since.”

Battlefield tours don’t necessarily attract the sort of people you might expect: on my excursion, among the military buffs, old buffers and a scattering of descendants of 20-somethings who came to Flanders and never left, are a hirsute, tattooed Alaskan blogger who barely glances up from his iPad and a singular, punctilious German anxious to point out that his father had worked for the Geheime Staatspolizei (aka Gestapo), but only as a clerk.

Le Fleming leads his motley band across the gently undulating countryside, conjuring up visions of legions of men bent upon each other’s destruction with a hideous array of what was then modern technology. Hellfire Corner, bombarded continuously by German artillery and once labelled “the most dangerous place on Earth”, is a mere roundabout today. Hill 60, beneath which Allied miners once exploded 24,000kg of explosives to dislodge the Germans, is a tree-covered slope. Telltale concrete bunkers and scattered memorials are almost the only reminders of the conflict. The overwhelming feeling is one of incredulity and fascination mixed with admiration that anyone could have put up with trench warfare for more than a few minutes.

Apart from the actual battlefields, there’s time to visit the area’s museums and examine the site where deserters were shot by firing squad, which raises questions about the morality of war as a whole.

Some of our party take photos and notes – in particular the Alaskan and the German, who sports a large leather-bound tome and a gold propelling pencil – but most exchange little more than desultory small talk and seem to be trying to come to terms with the evidence of history.

“The destruction wrought in Belgium has mostly been repaired, but the terrain has not changed very much and to walk over the ground on which these momentous events actually happened gives a far clearer insight than the reading of any number of books,” says Gordon Corrigan, an author and former racing secretary at the Hong Kong Jockey Club who now leads battlefield tours for London-based Martin Randall Travel.

“There are many companies and individuals who conduct battlefield tours and, as there is no regulatory mechanism, they vary widely from the highly competent and knowledgeable to those taking money on false pretences,” he says. “As a general rule, you get what you pay for.”

The best tour guides are those who can spice the warp and weft of a long-past conflict with vivid anecdotes and personal stories. During an unofficial truce on Christmas Day 1914, British and German soldiers played football in no-man’s-land. During the first Battle of Ypres, Khudadad Khan became the first South Asian to win the Victoria Cross, a British medal awarded for valour. German soldiers sang snatches of folk songs to identify themselves to fellow troops in the thick mist. Bordellos, marked by a blue lamp for officers and a red lamp for other ranks, did a roaring trade behind the Allied lines, and were often besieged by hordes of troops with their trousers folded over their arms. A century on, farmers’ ploughs are still turning up wartime scrap. And Private John Condon, who is buried at Poelcapelle cemetery, might just be one more casualty – until your eyes fall on the final words on his tombstone: “Aged 14.”

Indeed, the war cemeteries that dot this part of Belgium are the most poignant testament to the fallen.

They are immaculately tended and serve as a reminder of the fact that, while the war started in Europe, it soon spread around the world. Desperate for manpower, the Allies recruited able bodies wherever they could find them, including in Hong Kong and China. By war’s end, 96,000 men were working in the Chinese Labour Corps, and continued to do so after the armistice, filling in trenches, burying the dead and collecting scrap.

Hundreds died in the course of the clean-up, some blown up by mines or bombs, others killed by the flu pandemic that claimed more than 50 million lives around the globe.

Their tombstones, distinguished by both Roman lettering and Chinese characters, bear inscriptions such as “A Good Reputation Endures For Ever” and “Faithful Unto Death”.

A day on the battlefields is emotionally draining and physically tiring, and returning to Ypres – whose medieval Cloth Hall and gothic cathedral were rebuilt in accordance with the original plans after the war – offers a chance to chill and fill up at the Main Street Hotel. It’s a neatly conceived repository of fin-de-siècle funk, balancing modernism with contemporary comfort, serving bio juice at breakfast and inviting guests to partake of the “honesty” bar and a terrace where smokers aren’t so much corralled as hailed as a beleaguered band of heroes.

However, the day isn’t finished quite yet. Promptly at 8pm the traffic around the Menin Gate Memorial comes to a halt and scores of spectators gather as the Last Post is played by buglers from the town’s fire brigade. At once signifying the end of the day and symbolically summoning the spirits of the fallen, the notes infuse the evening air with an intensity that is pure goosebumps.

As he stands rigidly to attention next to me, the Gestapo clerk’s son’s face is immobile, except for the tears coursing down onto his neatly ironed field-grey shirt.