With a yell of "Let's RIDE!" the trailmaster pointed towards a cloud of dust on the flank of a nearby kopje and charged directly towards a horrifyingly wide gully. Feeling an answering surge from my own mount I tried to hold back from maximum horsepower, but Strider had committed us to the obstacle before I could even consider the alternatives.

Somehow we landed together on the other side, just in time to see the lead horse cut around a curtain of acacia thorns, leaning so low that the rider's leather chaps seemed almost to be in the dust. I gripped with my knees and gritted my teeth, and as we emerged onto a patch of sunlit savannah, I finally saw what we were heading towards.

Five or six big, sandy-coloured forms were cantering down the kopje in a direction that would intercept our path in the middle of the clearing. Eland are the biggest of the antelopes and even at this (rapidly diminishing) distance I could see that the animals in this bachelor herd were particularly impressive. The sound of the horses' hooves had tricked them into thinking that we were stampeding game; duped by their own instinct for safety in numbers, they were coming to join us. We would see this again and again with zebra and wildebeest. At one point we shadowed a herd of lolloping giraffe, but cantering with these huge eland bulls was beyond comparison.

We were at Mashatu Game Reserve, comprising 30,000ha of savannah, hardveld (so-called for its numerous rocky outcrops), riverine forest and mopane bush in Botswana's pristine Tuli Block. With the largest elephant population on private land anywhere in Africa (herds of up to 400 have been seen here), Mashatu is most famous as "The Land of the Giants".

The Tuli Block has remained almost unchanged since pioneers blazed these trails in the 19th century and as we had saddled up for our four-day patrol along the Limpopo Valley, I had felt like a raw recruit preparing for a Boer War skirmish. Trailmaster Steve Rufus's pre-ride briefing increased the feeling that we were penetrating hostile terrain. "If we find ourselves in predator territory, we maintain a united front, and unless I say "Go!" we hold the horses' heads quietly towards the cats." The other riders all seemed confident about this and, as we trotted away from Fort Jameson stables (characteristically named after the whisky rather than the statesman), I realised that for the next few days I would probably be the easiest meal ticket in the entire Tuli Block.

The first part of our trail followed the old Zeederberg coachline, which ran in the 1890s from Pretoria to Bulawayo. So many horses were lost to African horse-sickness that for a while zebra were used to haul the coaches. The small herd that watched with mild curiosity as Steve led us along the track was luckier than those draft zebra. "At this moment we're all illegal immigrants in Zimbabwe," said Steve. We were at the spot where the Zeederberg track bisects the 180 ° arc into which Zimbabwe encroaches beyond the natural border of the Shashe River. In 1891 there was allegedly an epidemic of lung disease among Botswanan cattle, so the British at Rhodesia's Fort Tuli ruled that the herdsmen must keep out of earshot of their cannon, which could be heard within a radius of 10 miles. Even as a relic of the frenzied days when colonial powers were carving up the Dark Continent along rivers, mountains or manmade gridlines, the Tuli Circle is a bizarre feature on the map.

We trotted onwards through mopane bush cropped back by Mashatu's 1200 nomadic elephants, and startled kudu, steenbok, warthog, jackal and a Spotted hyaena. Then on the open plains we fanned out to canter among wildebeest and snorting, pronking impala.

The timelessness of horseback travel seemed to bring to life the story of the Boer War siege at Bryce's Store (then a small local trading post). It seemed that, more than just passive observers, my horse and I had become part of bush life - though only as temporary guests, I hoped. The Boers shelled the store from Pitsani Kopje, where the emplacements can still be seen. Only two British soldiers survived the massacre, allegedly walking for three days to Fort Tuli to raise a punitive expedition against the Boers. Bullets, buckles and even cigarette cases are still occasionally found at the old Zeederberg camps and around the rubble of Bryce's Store.

Just when the heat (and our city-softened nether regions) became uncomfortable, we arrived in camp beneath three monumental mashatu (Nyala berry) trees, where Joyce and Sam greeted us with pre-dinner G&Ts.

Joyce Sesinyi is a Motswana lady who trained as a cordon bleu chef at an elite Okavango Delta lodge and now applies her astounding talents to a campfire potjie. She is a true perfectionist, quick to put the tough trailmaster in his place on the (not infrequent) occasions that his internal GPS malfunctions and the column arrives late for dinner. Joyce produced the best campfire cooking that I have ever eaten, actually selecting her firewood to add the last touch of subtle smoky seasoning to pizzas, quiches and impala stroganoff.

I was woken during the night by the whoop-whoooop laughter of a hyaena and the shrill scream of a baboon that had probably just become leopard fodder. We rose at dawn and as we breakfasted on fruit salad, freshly baked bread and blueberry muffins, a lion's cough echoed chillingly from the nearby scrub. The horses pulled nervously on the pony line and the threat was serious enough for Steve to decide on evasive action.

We set off in the opposite direction and rode straight into the heart of an elephant herd that must have been well over a hundred strong, a veritable pachyderm minefield that blocked our route at every turn. Each herd is known to Mashatu's rangers by the name of its leader (Scarflank, Charge, Right Hook) and as we found ourselves ever deeper in this maze of grey flesh and ivory, I began to hope that we had run into Floppy Ears' mob or, at worst, Stompette's.

After two hours Steve led us into a deep gully that would provide a route through the herd, but the horses' twitching ears alerted us to the presence of elephants pulling the trees apart just above our heads. Steve rode forward alone to check that the coast was clear. Just as he passed a crumbled part of the wall, a young bull elephant charged down into our little canyon.

The horses spun in panic and we fought to hold them in formation. But the tusker had been so intent on gaining the necessary momentum to push his bulk up the other bank that he hadn't even seen us. Giggling into our hands like truant schoolchildren trespassing in a farmer's field, we pointed our horses forward and continued on our way.