The gun-battle which erupted in the Liberian capital, Monrovia, hours before the United Nations took control of peacekeeping served as a stark reminder of how difficult their mission could prove.
A relatively small West African force has dramatically transformed Monrovia, where the guns are now mostly silent, and residents have started picking up the threads of a more-or-less normal life.
Now the UN must deploy across the country.
Peace remains fragile, even in Monrovia
The 3,500 West African troops, who arrived six weeks ago and saw President Charles Taylor into exile, have become the vanguard of a 15,000-strong UN force.
Off came the combat hats and on went the blue berets of the UN.
But even before they had officially arrived, they had been tested.
A gun-battle broke out between government forces and rebels as the peacekeepers escorted the main rebel leader, Sekou Conneh, to what should have been his first meeting with the interim President, Moses Blah.
The rebels were supposed to have been disarmed but weapons appeared from somewhere and three people died in the shoot-out.
The new head of the United Nations here, Jacques Klein, had a message for Liberians.
The West African peacekeepers swapped their combat helmets for blue berets
"It is time to put the past behind us, while not forgetting it. We are here with the full authority of the United Nations. We will use that authority to ensure your safety and well-being."
"For those still in opposition to the Accra [peace] agreement, who still continue to abuse their people, who continue to violate the agreements - time is running out for you. Your days are numbered and justice will ultimately prevail.
The regional peacekeepers have already made an impact in and around the capital city.
There is now a thriving market again where the heaviest of the battles were fought for control of the capital's strategic bridges.
There are no gunmen on the street, food prices have dropped to what they were before and people are living their lives again.
"Right now we can move freely. We feel that we are secure now with the presence of the international force. We feel that we can move freely," one man said.
But it is not all over. At the national stadium there are still 40,000 people living rough - two-thirds of those who took shelter from the fighting here after running away from their homes as the rebels advanced.
Some 40,000 people remain in Monrovia's football stadium
Many are living in the cramped space under the stands.
They have had no food for a month and they are scared to go home because their homes are in the areas the peacekeepers do not control yet.
"Because of insecurity I would not like to go back in the camp now," said one refugee.
"[The] disarmament that they talk about would bring freedom of movement to the Liberians. It has not commenced.
"What guarantee would I have when the people who have traumatised me they have not been disarmed?"
As the full United Nations force arrives it will slowly move out over the whole of the country, bringing the peace that the areas around Monrovia already know.
The orders are firm and clear, stopping a car load of civilians who want to drive through what was the front line between government forces and rebels.
Now white sandbags amongst the trees of the jungle are a checkpoint, the forward checkpoint, of West African peacekeepers.
It is as far forward as they have been able to go so far with just 3,500 men but they are determined that no fighters and no weapons will go through this point to jeopardise what is still a fragile peace here.
Captain Deku believes their presence has meant a lot.
"Since the force has arrived, the security situation has improved drastically and we have given the populace the needed confidence to go about their normal day to day activities."
Ready to disarm
The rebels we met welcomed the patrol and promised they will welcome the UN too.
A rebel captain who calls himself Alpha One says he wants to hand in his gun and go back to his studies.
"We don't have any conflict between us. We always do things together. So I think our relationship is very courteous.
"The arrival of the United Nations troops also, we happy to receive the people because we are happy for the war to finish in Liberia.
The United Nations know it won't all be easy-going but they have learnt lessons from their peacekeeping operation next door in Sierra Leone.
This time a huge force is planned from the outset and it comes with the strongest powers the UN can give it.
Everything now rests on whether Liberians really want peace here.