The Taoiseach, Mr Ahern, gave the Ulster Unionist Party (UUP) leader, Mr David Trimble, a written assurance about the historical importance of the Battle of the Boyne and Battle of Aughrim sites in relation to new roadway plans, an oral hearing has heard.
A copy of the Taoiseach's letter, dated June 22nd, 2001, was presented by An Taisce at the National Roads Authority's (NRA) oral hearing on a section of the M6 Dublin-Galway route in Galway city yesterday.
In the response to Mr Trimble, the Taoiseach said "Galway County Council and their consultants are aware of the historical importance of battlefields at Aughrim and you can be assured that full consideration of their significance will be taken into account during route design".
Mr Ahern noted in his letter that "the preliminary design for the new N6 route has only just commenced and the exact location is still under review".
An Taisce is opposed to the M6 routing through what historians have described as "Ireland's Gettysburg", where up to 9,000 people died in 1691.
It said yesterday that the Taoiseach had initially been informed about the site's significance in a letter to him on March 7th, 2001.
In a letter to Mr Ahern, Mr Cecil Kilpatrick, BSc, archivists of the Grand Orange Lodge of Ireland, warned that the M6 route would run "through the command post of the Williamite General Ginkel, through the position of the right wing of the Williamite Cavalry commanded by Huguenot General Ruvigny and through the site of a Williamite Gun Battery.
"Finally, the road would obliterate 'Lutterell's Pass'," and so have "equally devastating effects on the Jacobite positions".
Mr Kilpatrick also forwarded a similar letter to then first minister of the Northern Assembly, Mr Trimble, who sent it on to the Taoiseach.
In his response to Mr Trimble the Taoiseach said a meeting had been arranged with Mr Kilpatrick, the relevant county councils and their consultants in relation to route selection.
However, the Orange Order's concerns in relation to Aughrim were not assuaged after two such meetings, An Taisce's representatives said yesterday.
An Taisce said the Government was in breach of the spirit of the Belfast Agreement in relation to parity of esteem for two cultures.
Mr Greg Casey, solicitor for An Taisce, said at yesterday's hearing that it was "hard to believe that the proposed route goes straight through the very battle site, despite assurances from An Taoiseach to Mr Trimble".
The oral hearing, which opened on November 22nd last, is expected to finish this week.