MELILLA, Spain — More than 1,000 African migrants rushed toward the high fences topped with razor wire. They were met by the Moroccan police, who, with the support of the Spanish military police and a Spanish helicopter, thwarted their plan to scale the fences and enter Europe through this tiny Spanish enclave that clings to northern Morocco.

It was the second mass crossing to fail this week and one of the largest since May, when hundreds of migrants launched themselves at the fences on three separate occasions.

Worried about a surge in migration, the European Union authorities this year granted Spain 10 million euros, about $13.5 million, to reinforce the fences at Melilla and Ceuta, another Spanish enclave. Spanish officials have now covered them with wire mesh to make them harder to scale, creating an ever more elaborate obstacle course.

The new measures, combined with more aggressive policing on the Moroccan side, have reduced the number of migrants who succeeded in crossing since May, but seem to have done little to deter them from trying.

They attach hooks to their wrists and screws to their shoes for a better grip. Others climb barefoot. And so the game continues.

Once at the fence — actually three fences, two 20-feet high and a middle one that is slightly lower — it is speed that counts, those who have conquered it say. Some jump from one fence to the next, but often make crashing falls. Most of those interviewed said they climbed up and down each to make it over.

“You have to get over in one minute 30,” said Nili Onana, a basketball player from Cameroon, who made it over in a wave on May 28 and was interviewed in a short-stay center for immigrants in Melilla.

He was one of about 2,500 migrants who made it over the fence in the first five months of the year, more than the total for all of last year, according to Capt. Juan Gallego Esteban, who has headed the Spanish Civil Guard border force in Melilla for the last five years.

In interviews, both the migrants and the Spanish Civil Guard acknowledge that the mass actions are now carefully coordinated. The migrants said that before the jumps, they camp on the Moroccan side of the border for months, sometimes years, studying the movements of the Spanish border guards for patterns that might reveal any opening in the defenses.

Among those watching the border were former soldiers, Captain Esteban said. The authorities have also tried to seed the camps with informants who can alert them before the assaults begin. “We can stop them when they come two at a time, but if there are 2,000 at each point we cannot,” Captain Esteban said.

Increasingly, the mass jumps are aided by a talent for organization as well as social media and cellphones, the Spanish police and migrants say. Those who fail bide their time, and try again.

“I was up there for six months,” said Mr. Onana, describing his preparation before a mass jump on May 28, when 450 men and two women made it over.

“It is not easy. It is a study, you have to watch the way the Moroccan and Spanish guards work,” he said.

The largest group in the camp, about 1,500 migrants from Mali, organized a jump on May 1, when more than 1,000 migrants made a two-pronged assault. Another 200 made a jump on May 19. The Cameroonians made the next attempt on May 28, when 200 tried to storm the fence, the migrants said.

The man who led them was Renaud Taffou Nyame, known to his followers as the Prophet, a former security guard who said he had made 10 attempts in three years to cross into Europe, finally succeeding on May 28.

He bears a 20-inch scar down his left thigh and calf from a 20-foot fall from the fence onto razor wire in 2011. He cursed the Moroccan guards, who he said beat and spat at him as he lay wounded. The Spanish guards fired rubber bullets on his group crossing into Ceuta by sea in February, he added in an interview at the immigration center in Melilla. At least 15 immigrants died in that attempt, and Spanish officials have halted the use of rubber bullets since.

Dejected by his ninth failed attempt on May 1 when hundreds succeeded, Mr. Nyame says he prayed to God and saw a vision. He downloaded a Christian sermon onto his cellphone and listened repeatedly to its exhortations. Then he gathered fellow Cameroonians, together with others from Ivory Coast and Sierra Leone, and put out a message on Facebook: “This is the time to go.”

As hundreds of his countrymen, including his brother, gathered in the camp, he set the jump for May 30. Then in a surprise move to evade police informants, he woke everyone at 1 a.m. on the 28th.

At 4 a.m., they set off at a jog in a long line down the hill. They heard Spanish helicopters above, but within 30 minutes were at the fence evading the Moroccan police, in some cases leaping over their cars. “They call us monkeys, but I had been watching the guards and planning,” Mr. Nyame said.

There was a huge clamor as the jumpers chanted “Bosa,” a word that means victory and which sums up their struggle to get to Europe. “We adopted it — it means: ‘We have finished with the suffering,’ ” said Mr. Nyame’s brother, Wilfrid, who had been pulled down by Moroccan guards on a previous attempt.

One migrant, Francois, who had been trying to cross the fence for three years, said: “We were 700. We were shouting to encourage each other.” Like others, he gave only his first name because of fear of the police. “We don’t know how we climbed, it was by force of nature,” he said.

Some pulled off their shirts, so the police had less to grab. They wrapped clothes over the razor wire, but many emerged badly cut.

Over 50 men were wounded, some with broken bones, in the two jumps, Adil Akid, an activist of the Moroccan Association for Human Rights, said by telephone.

However difficult the journey and the jump, life back home was worse, several migrants said.

“It is anarchy in Cameroon,” said Achile, 37. “A country where there is no hope for young people, a country that kills its youth, not with a knife, but by 32 years of dictatorship.”

Their aims were simple. Wilfrid wanted to do hairdressing in Norway. Merlin, 22, from Cameroon, was aiming for Germany. “I like mechanics and I know they have good cars there. Maybe I will have a chance.”

-The New York Times