The auction house is calling it "quite possibly the finest collection of patriotic posters relating to World War I."
But come July 1, Edward H McCrahon's 2,000-strong assortment of first world war posters will be a collection no more.
Because each item is going under the hammer on June 30 and July 1 at Guernsey's online sale.
Around half the collection features US Great War posters, with the remainder spanning the other countries who took part in the conflict.
Of particular interest to collectors will be the large number of posters that are thought unique.
"Although all are patriotic at their roots, this Collection features posters that cover fundraising, food rationing, enlistment, women's war efforts, and animal aid," explains Guernsey's.
"Of note are the many foreign language posters printed here in the United States that functioned as outreach to the large clusters of immigrants in cities such as New York."
A passionate believer in the Allied cause, McCrahon joined the French army two years before the US entered the arena. When America declared war in 1917, he enlisted and rose to the rank of colonel.
It was during his stint with the French army that McCrahon became fascinated by war poster art, and at war's end he embarked on 16 years' of collecting the finest examples.
The items all have superb provenance as they are consigned directly from McCrahon's grandchildren.
Estimates range from $300 to $7,000.
Click here to see our rare posters for sale.
Please sign up to our free newsletter to receive exciting news about militaria auctions.
View our stock items for sale | Portfolios for sale
Guides and analysis
Investing in Art | 10 reasons to invest in collectibles | Which asset is right for you?