Dougherty?

A few minutes of online research informs me that my grandfather's grandfather emigrated from Ireland to Manhattan in 1860...later, the clan moved upstate to Ithaca and later to Florida. That makes me a 4th generation American. 

My grandfather, Earl Dougherty served in WW1.  Contemporary news reports state that only 10% of his Division returned

My father, Harry Dougherty, was a WWII veteran who drove a half-track through France and Germany.

I flew cargo into Vietnam for several years on long Pacific island-hopping missions.

My son and grandchildren have been spared...

"Who so ever asks me of my birth...

I will tell them I am born of Irish Princes who ruled in Donegal

a thousand years ago; that I am descended from the High Kings of Ireland,

and my name is from the Clann ÓDochartaigh!"

This notable surname is an Anglicized form of the Old Gaelic "O'Dochartaigh", descendant of Dochartach, a personal byname meaning "Hurtful, Injurious". 

Traditionally, Irish family names are taken from the heads of tribes, revered elders, or some illustrious warrior, and are usually prefixed by "Mac" denoting "son of", and "O", grandson, male descendant of. 

 By the 14th Century the O'Dochartaigh chiefs had extended their territory till they became Lords of Inishowen, and their headquarters was on the Inishowen Peninsula. 

The power of the O'Dohertys was greatly reduced following the ill-timed rebellion of 1608 led by Sir Cahir O'Doherty, and several of the clan fled to Scotland, the Isle of Man, and England, where the name was variously Anglicized as Do(u)gherty, Daughterty, Docherty and Docharty. 

The family Coat of Arms is a silver shield with a red stag springing, on a green chief three mullets of the first. 

The first recorded spelling of the family name is shown to be that of Donnall O'Dochartaigh, which was dated 1119, in the "Manx Names", by A. W. Moore, during the reign of Turlough Mor O'Conor, High King of Ireland, 1119 - 1156. 

Surnames became necessary when governments introduced personal taxation. In England this was known as Poll Tax. Throughout the centuries, surnames in every country have continued to "develop" often leading to an astonishing 140 variants (or more) of the original spelling.