The region of Flanders is in which of these countries?

I recommend reading: In Flander's Field - a poem by Lieutenant-Colonel John McCrae.

QuizzMister, yes, it was part of a WWI commemoration - all of the 888,000 ceramic poppies planted by volunteers, one for each of the British Empire soldiers killed - from the website: “In 2014 the Tower of London marked the centenary of the outbreak of The First World War (WWI) with the commemorative art installation Blood Swept Lands and Seas of Red, which saw the moat filled with thousands of ceramic poppies. In 2018 the Tower once again became a site of commemoration, marking 100 years since the end of WWI with Beyond the Deepening Shadow. The nightly candle lighting ceremony in the moat was led by the Yeoman Warders and created a circle of light radiating from the Tower as a symbol of remembrance. Both commemorative events at the Tower were part of the world-wide, First World War centenary commemorations that began on 28 July 2014 and ended on 11 November 2018.”

The photo is the Tower of London