The Battle of Prestonpans 1745 Heritage Trust is strongly opposing plans by two renewable energy companies to construct a huge electric substation on the site in East Lothian.
Executive Trustee Arran Johnston said they were shocked when the initial plans for the site were unveiled given its status in Scotland's history.
The ground was home to the first significant conflict in the 1745 Jacobite Rising where Bonnie Prince Charles's army unexpectedly defeated government troops in the early hours of the morning on September 21.
The substation will be the only one for the project onshore and will link to the Inch Cape Offshore Wind Farm which is to be built 15-22 km off the coast of Angus. The farms, which will have up to 213 wind turbines, will be linked to five offshore substations.
Mr Johnston said: "We were shocked when we first heard of the proposal to build a great big metal eyesore smack, bang in the middle of the battlefield."
A spokeswoman for the wind farm said: "The proposed onshore site was identified following an assessment of a variety of potential landfall and substation locations in East Lothian."