Hundreds of English and Welsh soldiers perished in the battle

The 30-acre hillside pasture is part of the Pilleth estate near Knighton, Powys, which is valued at �1.4m.

The Save Bryn Glas group said it had written to Welsh celebrities for help to buy the land for the nation, but received no replies.

Tenders for the estate must be submitted by midday on Tuesday.

The battlefield, known as Bryn Glas, is part of a 168-acre lot worth �445,000.

Group chairman Albert Ward said he and his colleagues had had only seven weeks to try to raise the money.

Without a benefactor we're unable to press ahead with plans to buy the battlefield Albert Ward

The Welsh Historical Forum, made up of about 35 groups, including the Friends of Pilleth and the Owain Glyndwr Society, formed the Save Bryn Glas group in May.

"We've written to a few famous Welsh people and people with connections to Wales, but we haven't received any replies," he said.

"Without a benefactor we're unable to press ahead with plans to buy the battlefield."

In May, Francis Chester-Master, director of the firm selling the estate, said it was unlikely the lot containing the battlefield would be split in two to lower the price.

That same month, Brecon and Radnorshire MP Roger Williams wrote to Culture Minister Alun Pugh urging the Welsh Assembly Government to help buy the land for the nation.

However, Mr Pugh wrote back saying it was not the assembly government's responsibility to involve itself in the sale of private land.

Landmark victory

Mr Williams said at the time: "Battlefields are an important part of a nation's heritage and I believe it is essential to preserve Pilleth battlefield and to open it to the public."

The Battle of Pilleth in June 1402 was a landmark victory in Glyndwr's fight for Welsh independence from England.

He defeated an English force led by Edmund Mortimer, one of King Henry IV's barons.

Pilleth estate is made up of some 585 acres, and is being sold by Sir Robert Green Price.