The memorial is for a local hero who died while serving in Afghanistan.
The monument is dedicated to Fusilier Louis Carter who died while serving in Afghanistan in 2009. He was helping a wounded colleague at the time.
Nuneaton Police have said that the local community has reacted to the vandalism with anger and disgust.
The damage was discovered and reported to police on the morning of Remembrance Sunday.
Sergeant Martin Hewish from Nuneaton Safer Neighbourhood Team said: “The local community has understandably reacted with anger and disgust at the damage caused to this memorial to a local hero who gave his life in defence of this country.
“We share this sentiment and are committed to finding out who is responsible. We’d like to hear from anyone who can help us identify the person who caused this damage.”
Anyone who recognises the tag or has any information that can help officers identify who is responsible for causing the damage is asked to report it at www.warwickshire.police.uk/report or by calling 101. Alternatively, information can be provided anonymously to the independent charity Crimestoppers on 0800 555 111.