Northumbria Police used number plate recognition technology to track suspected thieves, paid close attention to scrapyards and acted on tip-offs about who could be responsible for stealing lead, copper and cable.
The rising international price of lead and other metals has caused an increase in thefts from roofs, pipes inside homes and even cables from railway lines.
Detective Inspector Steve Patrick, who led the operation, said: "The rise in metal theft is a national issue and we are using a variety of resources to tackle the problem in Northumberland.
"Thieves are not only targeting construction sites and public buildings, they will seize any opportunity to steal metal.
"The Stocksfield war memorial has had its brass plaque stolen and numerous properties have had lead stolen from their roofs across the county.
"This operation has shown we are targeting the right people and we will continue to keep them in our sights. The information and intelligence we have gathered during the course of the operation will be used in the coming months.
"We also need the public help us - if people see suspicious activity or vehicles which seem out of place they need to let us know so we can take action."