Inside some 40 members of the British "Convoy of Hope" are distributing presents to beaming kids. Four hundred meters away, amongst the evergreens, sit the Serbs. Two years ago they took 34 tanks through the town, firing at everything that moved. One man had to defend the school on his own for 12 days. His photocopied picture adorns the walls of the local cafés. He's since had a nervous breakdown.

The locals were shocked. The two communities, Croatian and Serbian, had lived side by side for generations. Now every building bears the scar of battle. The large man with the Palestinian scarf is a British member of the Convoy. He has just discovered how the Serbs allegedly killed Croatian children in a particularly gruesome manner.

It's not as bad as it could be, though. At least here the buildings are still standing - unlike villages such as Lipik, a few kilometres away. The Croats build their villages along the main road. In Lipik not one house, shop or monument is left standing. Snow softens the eerie, graffiti-covered ruins.

When the Serbs pulled out last January, it allowed people such as Tony Budell, who leads "Konvoj Nade", the Convoy of Hope, to bring aid to those left behind. Together with his wife and a devoted set of followers, they have brought over 21 convoys to the shakey peace of the new republic.

A tall charismatic man, tanned, with swept greying hair, Budell is a focal point for the whole convoy. Volunteers from across the UK, and several other countries, flock to join him every month. They form a strange band; evangelicals, church elders, nurses, pilots, ex-SAS servicemen, OAPs - in fact, the 44 team members represent just about every denomination you could think of.

What motivates them? "I used to be very selfish, very arrogant, I was a scumbag if you like," says the 50 year old Budell, an ex-trucker now living in Canterbury. "I was a total aetheist. Then I found God. One day I sat on a bench at Dover waiting for my customs papers. I was going through a marriage breakup at the time and living in my lorry. I heard someone calling my name. There was no-one there. Then I realised that the voice was inside and it said 'I am going to give you the spiritual strength to carry other peoples' crosses and I will carry yours'."

That was on 12 May 1988. Since then Budell has devoted himself to charity, working with Romanian and Croatian refugees. He and his new wife, Val, also became devotees of the Indian avatar, Sri Sathya Sai Baba, preaching, (in his words) "universal love." Several other members of convoy 21 are devotees.

The mood is one of optimism, the atmosphere like an adventure holiday. CB chatter crowds channel 30. Everyone enjoys using their new 'handles'; Catweasel, Girls On Top, Echo 1 (Budell), Polecat, Werewolf, Smokey Joe, Air Angels. "Eyeball, eyeball!" they shout as they spot one another.

For many this is their first trip. The two day drive through France, Belgium, Germany and Austria has been uneventful. Even Slovenia, the first breakaway republic, is remarkably serene (few will remember that a war was fought there against the Yugoslav federal army).

At the Slovenian-Croatian border the 21 vehicles - ambulances, transits, cars, trailers and one HGV - nervously line up. Once across, with an hour's wait for paperwork, the tension breaks. Two English girls set up an impromptu aerobics class next to their van, music pumping from a ghetto blaster. The younger, more religious members of the convoy leap up and down in the middle of the road. Someone switches on the strobe atop an ambulance. Gunfire can be heard in the distance as the sun sets.

December 6, Croatian Christmas, St Nicholas' Day when presents are exchanged. The convoy rolls through untouched villages, rotting maize poking through fields of snow to either side of the road. The twin ambers flashing above Tony's van draw the convoy, his flock, at a steady 35 mph through the mist. We pass many priests and shrines.

The city of Slavonski Brod (pronounced "Brode") sits next to a river; the Croatians on one side, the Bosnian Serb army on the other. First sight of traffic policemen, Coca-Cola lorries, bustling markets, shops filled with goods and golden Christmas trees. Tony says that no-one can afford to buy from the shops.

Dark brick tower blocks parade next to a main thoroughfare. One houses refugees from Bosnia and eastern Croatia. Graffiti, "Iron Maiden", "Metallica" and "AC/DC", is splashed across the walls. Shrapnel marks pot the brick. Kids dressed in Nike trainers and western jeans crowd around the vehicles. A stern-faced, old man stares and walks around us as we pull in.

Juice is handed out by middle aged ladies in a backroom. Outside a young Mancunian is trying to argue the merits of communism with a milita man. A crowd of boys hems him in. The smaller ones are searching his pockets. When the back of an ambulance is opened to distribute sweets, there are scuffles.

Most of the boys are locals, about 14, wear earrings, love basketball and listen to heavy metal. They say they want peace. Srotan Kostadinovic, a 14 year old in a camouflage jacket, tells me he wants to be a soldier and offers to sell me explosives, bullets, whatever I want. He is a cheery young man, with the first signs of a moustache poking through his upper lip. He hates the UN. All the boys do.

With halting English, they point to where a classmate died from a falling artillery shell. "Howbitzer" they call it. Serb snipers shimmied up a tree to assasinate a local dignatory and his sleeping family in their home the other day. The damage has now been repaired. A milita man holding his baby son proudly displays a set of photos taken in Mostar (Bosnia) where he's been on active service. A mortar round explodes in the distance as a child plays with bullets in the snow, discarded wrapping paper blowing limply across the slush.

We have to leave because our paperwork is not in order. The rules have changed since Tony's last visit. He struts up and down in his crumpled boiler suit in a rage, cursing and cussing. One of our number returns from a jaunt across the border - he's been to buy a loaf of bread. A youth with lank long hair creeps between the vans, trying to sell an 88mm artillery round. A sense of unreality creeps in. That evening there is a battle as the Serbs cross the river.

David Harris, a 76 year old church elder who describes himself as "a crossbreed of Aberdeen and Arbroath" is shocked by the situation in Pakrac. "The idiocy of it all...you cannot believe it. Houses are just bombed - one stands whilst the other falls. Just think of ethnic cleansing in England. All the Scots would have to go home, clambering over Hadrian's Wall. Just think of it." He's left grandchildren to come out here. It clearly upsets him. One policeman tells him it's better to believe in the stars than in God.

Canadian UN soldiers patrol the front line, only 400 meters away. Anneka Rice's school, built for the Challenge An(n)eka programme, lies empty and unused. The Serb snipers can easily shoot the children.

Behind us lies the town hospital, once the pride of the health service. The top set of windows are still intact, as are the red cross signs painted on the roof. The rest withered two years ago under a maze of rocket propelled grenades; 2,000 in a single day. Now an outbuilding serves as the refugee centre and an ancillary unit functions as the main casualty area. It's warm inside and there is real toilet paper - albeit of the eastern bloc variety.

Behind the refugee centre stands the old mental hospital, a fine old buidling now strewn with bullet holes and broken beds. The Serbs executed the 400 children inside. The Canadians have failed to find the mass grave they presume must lie nearby.

About half the medical aid is unloaded, passing down a long chain of refugees and locals into storage. The older women wear scarves, the younger have western-style makeup. Later we all share a mass meal.

Croatian beer, "Osjecko pivo" (12%) and £3 (per litre) bottles of gin soon loosen tongues. The town still has several bars intact - it doesn't take long for the convoy members to find them. The weather has prevented us from leaving, so we watch Sky News and MTV on one of the town's surviving TV sets instead. In turn we are watched by the local police. At 12 midnight a stream of cursing and bumping bodies makes it's way back to the camp, lookout towers burning bright overhead on the Serbian-held hillsides. Most of the hospital beds are occupied by casualities of drink, not war, that night.

The final leg of the journey. The aim is to unload the rest of the aid at two refugee camps, Ranginekova and Spansko, which lie on the outskirts of the Croatian capital. The convoy still lacks 'official' paperwork (the right palm hasn't been greased) but Tony is in firebrand mood and won't stand for bureaucracy - his policy is now to ignore it. "My faith makes me indestructible" he confides.

Leaving Pakrac, the convoy halts by the old school to give presents to the kids. The children are ecstatic; teachers smile and share plum brandy with the foreigners. The noise is deafening, bullet holes sobering. Many of the adults are close to tears. Some obviously find it hard to leave.

We find the same feelings, only intensified, once in the camps. In Ranginekova, 12 year old Miroslav Antun stands shivering in his new purple denim coat, hand held in mine. He's worried that the farm workers will steal the coat from him, when they return from work later that evening. The locals resent the newcomers - there may be trouble between the men of the two communities if the presents, food, clothing and toys, aren't properly hidden. This is the way of things in a war zone.

"It is very difficult," says Miroslav in good English. "Nobody can do anything. We get some money from my uncle in Switzerland, but only 100,000 dinars (£10) a month from the government."

The refugees, Bosnian Croats, share rooms in numbered wooden barracks. Each family, perhaps five to eight members, lives in a single, closet-sized space. There are only a few men with them. The older ones speak German, having fought in the Second World War. The younger are all ex-militia, smoking thin rollups in the cold.

As the freezing fog creeps between the washing lines, Miroslav's mother invites me inside. A deeply hospitable woman, she insists on providing a carton of German apple juice before asking if I want to keep her rosary. It's very embarrassing - she has so little, almost nothing in fact, so I refuse.

Presents from the convoy lie strewn on the bed. The family album sits on top of the TV, lying on the Coca-Cola tablecloth. Miroslav's father is a handsome man, a former factory manager shown in his soldier's uniform. The old English lady who's followed me indicates her approval, causing gales of laughter. Miroslav's hazel eyes widen as he flicks through pictures of his home town, Johovac, from which the family fled a year ago.

Many of the children are still at the camp school. They attend in shifts. Miroslav doesn't want to let go of my hand. His mother wipes away tears as we walk outside again. It's very difficult to drag ourselves away. I slip my Swiss Army knife into the boy's pocket, only later realising I should have given him some food. By now the aid parcels are being swiftly distributed amongst the families. It won't be long before the farm workers return.

Standing amongst the mud and slush, another old lady hugs Miroslav and tells his mother: "He has a good heart, such a good heart." He grimaces and replies: "No, Croatian heart."

A terrible blizzard settles on the city as the convoy splits, each vehicle making its own way home, or travelling further south to Bosnia. Other convoys continue to stream in and out of the country; part of Konvoj Nade's medical aid, for example, is sent to Nova Bila, a Croat town surrounded by Muslims in Bosnia.

In Germany, our three transits encounter an old Croat from Amsterdam, taking two lorries and a van full of clothes and Christmas presents to Zagreb. Sally Becker, the British aid worker and so-called'Angel of Mostar', departs in a huge convoy for Bosnia on the evening we board the return ferry. In a break between stories of his 'former' life, Tony Budell says he's going to Sarajevo and Mostar in January. In Belgrade, the nationalists have just won elections backed by promises of a Greater Serbia. They vow to take back Pakrac and other towns before the new year ends.