VisitScotland revealed the "Bannockburn Live" event, which was due to take place over three days, will now only take place on Saturday 28 and Sunday 29 June.
The event has been cut following fears over low ticket sales. Organisers say so far 2000 tickets have been sold for the event, which hoped to attract 45,000 visitors.
National Armed Forces Day is also due to take place in Stirling on the Saturday.
A VisitScotland statement said: "This change allows for significantly more event activity to take place than originally planned, and ensures operational coordination with Armed Forces Day on the Saturday."
The Battle of Bannockburn on June 24, 1314 is one of the most significant events in Scottish history.
Robert the Bruce led the Scots to a decisive victory over the forces of King Edward II of England at the battle site near Stirling.
The Bannockburn Live event will include a large-scale "brutally realistic" re-enactment involving 300 people, taking place three times each day.
Mike Cantlay, chairman of VisitScotland, said: "VisitScotland wanted to ensure that locals, visitors and businesses alike benefitted from this big weekend on the Homecoming calendar, and ensure a smooth and safe event operation for all."
Mike Robbins, Labour Provost of Stirling Council, which has been criticised for hosting Armed Forces Day alongside Bannockburn Live, made no mention of the celebrations for the 700th anniversary.
He said: "As part of Stirling's most exciting weekend ever, we're looking forward to recognising and celebrating the contribution made by our Armed Forces with spectacular displays and activities for all the family."