Why did the old man shake his head? Who found the skull?

From -Treasure Trove Poetry workbook
Poem: After Blenheim
Why did the old man shake his head? Who found the skull?

The old man shook his head to reflect the disappointment at the war that took place years ago only to claim innocent lives. The old man was Kasper, and his grandchild Peterkin found the skull beside the small stream where he was playing.