1 Samuel 31:2

And the Philistines followed hard upon Saul and upon his sons. — “The details of the battle are but seen in broken snatches, as in the short scene of a battle acted upon the stage, or beheld at remote glimpses by an accidental spectator. But amidst the showers of arrows from the Philistine archers, or pressed hard even on the mountain side by their charioteers, the figure of the king emerges from the darkness. His three sons have fallen before him; his armourbearer lies dead beside him.” — Stanley: Jewish Church, Lect. 21

And the Philistines slew Jonathan, and Abinadab, and Melchi-shua, Saul’s sons. — But while, in his own record of the national disaster, the compiler or historian, in his stern sorrow, expunges every detail, and represses every expression of feeling, he gives us in the next chapter (2 Samuel 1:1) the stately elegy, in the beautiful moving words which the successor to the throne wrote on the death of the first king and his heroic son. Without comment he copies into his record the hymn of David on Saul and Jonathan, just as he found it in the Book of Jashar (the collection of national odes celebrating the heroes of the Theocracy). “There David speaks of the Saul of earlier times — the mighty conqueror, the delight of his people, the father of his beloved and faithful friend — like him in life, united with him in death.” (Stanley).

“Saul and Jonathan were lovely and pleasant in their lives
And in their death they were not divided.
Than eagles they were swifter, than lions more strong.”

(2 Samuel 1:23.) From the lost Book of Jashar.

Nothing is known of the two younger princes who fell fighting here by their father’s side, sword in hand against the enemies of their country.
The hero Jonathan and his two brave brothers, as far as we can gather from the scanty details of the battle after the army was routed in the valley of Jezreel, retreated (fighting all the while) to the hill of Gilboa. There, it seems, they made the last stand with the fideles of the royal house of Saul (1 Samuel 31:6), and there, no doubt defending the king to the last, they fell.