His date of birth is uncertain, but since he saw combat in 1402, was Lord Deputy of Ireland in 1406 and Prior of Kilmainham by 1410, it must have been long before his first legitimate brother was born in 1392, and probably several years before his father's first marriage in 1386.
Thomas' Gaelic nickname Bacach, "the lame" indicates that he was crippled,[2] but this disability did not stop him from pursuing a highly successful military career.
He was made Lord Deputy of Ireland in the absence of Thomas of Lancaster, Duke of Clarence in 1406, in which office he exercised great political influence.
Although accounts of the battle are confused, it seems clear that Drake rallied his men and defeated the O'Byrnes on the banks of the River Dargle near Bray, County Wicklow.
[6] Boteller's rule as Lord Chancellor had by now become so unpopular that the Privy Council of Ireland sent an impressive deputation, including two archbishops, to England to complain about his misconduct, and he was summoned to London to answer the charges made against him.
Thomas was accused of treasonable correspondence with Gerald FitzGerald, 5th Earl of Kildare and Christopher Preston, 2nd Baron Gormanston, both of whom were briefly imprisoned.
Preston and Gormanston were soon released and restored to favour: Otway-Ruthven concludes that they are unlikely to have been engaged in a treasonable conspiracy, and were simply opposed to Shrewsbury's high-handed regime.
O'Flanagan[2] calls Thomas a man of great courage and considerable administrative ability, who overcame what were then the serious double drawbacks of illegitimacy and physical disability to become a successful soldier and statesman.