A massive security operation was launched today as the British army moved in to fortify the surroundings of Drumcree Church in Portadown.
Large numbers of troops with heavy equipment worked all day to block any attempt by Orange Order marchers to reach the flashpoint Garvaghy Road tomorrow.
The heavy barrier which is traditionally used to block the bridge below the church was set up by army engineers this afternoon.
Despite the undoubted size of the security operation, it was smaller than that seen in previous years, reflecting the optimism of police chiefs that there will be no major trouble this year.
However, no chances were taken with the preparations after scaled down security measures last year were met with loyalist violence.
A British army spokesman said the main barrier across the bridge was smaller than that seen in earlier years, but more robust than the one which was stormed by protesters in 2002.
Military vehicles loaded with heavy fortifications, including heavy earth moving equipment, concrete blocks and fencing, arrived at the scene throughout the day.
As helicopters buzzed overhead, army engineers erected concrete barriers and razor wire fences in the fields off Drumcree Road.
Soldiers also put up barriers around St John's Roman Catholic Church at the top of the Garvaghy Road and troops were stationed along part of the parade route in Obins Street in Portadown.
Marchers from Portadown Orange Lodge will arrive at Drumcree Parish Church tomorrow morning and will attempt to march back into Portadown via the mainly nationalist Garvaghy Road, against the wishes of residents.
However, they will find their way blocked as it has been for the previous five years following decisions by the Northern Ireland Parades Commission, which rules on contentious marches.
Violence has flared at the march ever since the first stand-off between loyalists and the security forces in 1995.
Orangemen have been banned from walking along the Garvaghy Road since 1998 because of the objections of Catholics and nationalist residents, a move which has sparked loyalist violence across Northern Ireland.
However, hopes have been raised this year that an end to the stand-off may be in sight.
In a bid to end the blockade, the leadership of the local Orange Lodge agreed for the first time to hold face to face talks with the residents, which they want to be chaired by Downing Street aide Mr Jonathan Powell.
One proposal involved permission to march this Sunday, with any future parade requiring the consent of the residents.
No meetings have yet taken place, however, and the Parades Commission, has not been asked to review its decision this year.
The police officer in charge of the security operation, Assistant Chief Constable Stephen White, and the heads of all the main Protestant Churches have appealed for calm ahead of this year's parade, which commemorates the anniversary of the battle of the Somme.
Chief Constable Hugh Orde said police hoped to mount a relatively low-key operation tomorrow during a visit to the scene today.
"We've met with everybody that wants to talk to us about this event to make sure we can accommodate everyone's human rights as best as we possibly can," he said.
"I am quietly optimistic that with the officers we've got here and the army supporting us, we should have a peaceful day."
A British army spokesman also said soldiers would be maintaining a low-profile presence after the security measures were put in place.
However, he insisted more troops were stationed nearby if required to support the police.