SEA King helicopters whirred to and fro across Dartmoor on Sunday as more than 2,000 teenagers were evacuated from wilderness campsites, and the Ten Tors Challenge was abandoned for only the second time in its 47-year history. The decision to halt the two-day annual event was made on Saturday evening, after a day of strong gusting winds and heavy rainfall — and with the threat of more torrential rain for the following morning. The event began with glints of sunshine, expectant smiles, and the hopeful arc of a rainbow at 7am on Saturday. Almost 2,400 people, aged between 14 and 20, fanned out across the moor on expeditions of either 35, 45 or 55 miles. But even at that stage, a handful of teams had decided not to set off because of bad weather warnings. During the day, low cloud settled on the moor, decreasing visibility, and rain began to fall heavily, persuading around 50 more teams to give up. At 6.10pm, it was decided to hold teams at their next tor, and at 9pm the army made the decision to go ahead with a controlled move off the moor. Paul Vachon, controller of the North Dartmoor Search and Rescue Team, based in Okehampton, said: 'Safety was our great concern. The rain was saturating the moor very quickly because of the rainfall we'd had earlier in the week. 'We were monitoring rivers from early on Saturday and with the forecast for heavy rain early on Sunday morning, we knew they would fill up, and we were concerned that with the low cloud, air rescue might not be able to get to teams in trouble.' More than 700 military personnel, police, and rescue workers co-ordinated their efforts to airlift, drive, and escort the teenagers off the moor. Among those airlifted were team-mates of Charlotte Shaw, 14, from Edgehill College, Bideford, who died after falling into a rain-swollen stream on Dartmoor on March 4 while training for the challenge. Paul Vachon said he was amazed at how smoothly the operation had gone: 'The military did an exceptional job, especially the navy pilots who were flying in very poor conditions.' The rescued teenagers were each awarded a Ten Tors medal, despite not being able to complete the challenge. Teachers, rescue leaders and the army were unanimous in stating that halting the event had been the right decision. The Ten Tors was last cancelled in May 1996 because of poor visibility and freezing temperatures. The effects of the rain this year were magnified on those areas of the moor where rivers funnel into flat, marshy areas. On Sunday morning, North Dartmoor Search and Rescue Team measured water levels in Wallabrook. Paul Vachon said: 'At six o'clock the water was below our knees, but one hour later it was above our waists — that gives you some idea of what conditions were like.' The necessity to halt this year's Ten Tors wasn't all bad news. Lt Col Tony Clarke, commander of the Dartmoor Training area, said: 'The troops involved in the operation gained enormous training value from it. It was exactly the sort of operation that the army has to carry out in Iraq or Afghanistan.' l See pages 16 & 49.