Complex sentence: When Dundas replied favourably to the rebels overture for peace, they delivered terms--they would surrender themselves and their arms and return to their homes, provided the free-quarters would end and plundered property was restored.
Split into simpler sentences: When Dundas replied favourably to the rebels overture for peace, they delivered terms. They would surrender themselves and their arms and return to their homes, provided the free-quarters would end and plundered property was restored.