Little of note occurred during Hador's rule. On the three hundredth anniversary of the Stewards' Reckoning, the calendar introduced by his ancestor Mardil, he added an extra day to the year to 'fine-tune' the calendar's accuracy. Hador ruled during the time of the Watchful Peace, and so had no need to concern himself with matters of war, though his descendants would not be so fortunate.
Hador ruled Gondor for one hundred and seventeen years (an exceptional long rule - Hador was the last of the Gondorian rulers to live for more than a hundred and fifty years until the time of Aragorn). He was succeeded by his son Barahir.
The date of Hador's birth appears only in The History of Middle-earth volume 12, The Peoples of Middle-earth. It cannot therefore be considered completely reliable.