This is the most famous poem of the First World War. "Dulce et Decorum est Pro patria mori" means "It's sweet and fitting to die for one's country" In latin, the word patria means native land, hence patriotism. Patria sounds like pater, meaning father.
"Five nines" were German 5.9 inch artillery shells which made a hooting noise as they passed through the air.
"Outstripped" meant that the shells hadn't got enough range to reach the withdrawing troops. If you win a race you outstrip other runners.
The gas was chlorine which is green and heavy. Soldiers choose to follow low ground or dug trenches to shield them from gunfire and shrapnel. But the chlorine fills hollows, destroying the lungs of soldiers and choking them to death. The gas was more concentrated near the ground, getting to higher level could save them. Within the lungs chlorine makes corrosive hydrochloric acid. There was no treatment, nothing could be done to save their lives.
Chlorine smells like household bleach which works by oxidising organic matter. Oddly enough ordinary table salt is a compound of chlorine gas and sodium metal, which is unstable soft and silvery and it burns violently on contact with water: sodium chloride. Two dangerous elements make salt which is relatively harmless - the sea's full of it.
Dilute "chlorine water" was one of the first disinfectants, surgeons washed their hands in it. Chlorine is used to disinfect swimming pools, but the strong characteristic smell of public pools isn't chlorine, it's a compound made when chlorine combines with urine, so don't piss in the pool, kids.
The Germans first used chlorine in April 1915 and about three months later the troops were issued with respirators. Before that they had used pads soaked with stale urine because the ammonia counteracted chlorine. Later a mixture of chlorine and phosgene was used because it disabled soldiers immediately. Later still there was mustard gas, a liquid and even one drop on the skin would inflict horrible injury.
In Latin Dulce would have been pronounced with a hard c - dool-key. In Italian it's Doll-chay. The pronunciation I use is the anglicised Dull-sea, like the girl's name Dulcie, because that's what's in current use. Language is a living thing and there's no point in clinging to anacronisms.
"Gassed" was painted by John Singer Sargent in 1918 and it's in the Imperial War Museum in London.
The "friend" he was addressing was Jessie Pope, who wrote this:
Whos for the game, the biggest thats played,
The red crashing game of a fight?
Wholl grip and tackle the job unafraid?
And who thinks hed rather sit tight?
Wholl toe the line for the signal to Go!?
Wholl give his country a hand?
Who wants a turn to himself in the show?
And who wants a seat in the stand?
Who knows it wont be a picnic not much-
Yet eagerly shoulders a gun?
Who would much rather come back with a crutch
Than lie low and be out of the fun?
Come along, lads
But youll come on all right
For theres only one course to pursue,
Your country is up to her neck in a fight,
And shes looking and calling for you.
Here's an excellent reading by a young man who sounds like Wilfred Owen might have sounded, a disillusioned and angry young officer.