He was supposed by the earlier chroniclers to have been the ostler of Vytenis, prince of Lithuania, but more probably he was Vytenis' younger brother and the son of Pukuveras Liutauras, another Lithuanian prince. In any case, his purported Rurikid origin was a later fake. According to the latest research, even his grandfather cannot be named with certainty. Gediminas became Grand Duke (Didysis Kunigaikštis) of Lithuania in 1316 at the age of forty and ruled for 25 years.
Choice of religion
He inherited a vast domain, comprising Lithuania proper, Samogitia, Red Russia, Polotsk and Minsk; but these possessions were environed by powerful and greedy foes, the most dangerous of them being the Teutonic Knights and the Livonian Brothers of the Sword. The systematic raiding of Lithuania by the knights under the pretext of converting it had long since united all the Lithuanian tribes against the common enemy; but Gediminas aimed at establishing a dynasty which should make Lithuania not merely secure but mighty, and for this purpose he entered into direct diplomatic negotiations with the Holy See. At the end of 1322 he sent letters to Pope John XXII soliciting his protection against the persecution of the knights, informing him of the privileges already granted to the Dominicans and the Franciscans in Lithuania for the preaching of God's Word, and desiring that legates should be sent to receive him also into the bosom of the church.
On receiving a favorable reply from the Holy See, Gediminas issued circular letters, dated 25th of January 1325, to the principal Hansa towns, offering a free access into his domains to men of every order and profession from nobles and knights to tillers of the soil. The immigrants were to choose their own settlements and be governed by their own laws. Priests and monks were also invited to come and build churches at Vilnius and Novogrodek. In October 1323 representatives of the archbishop of Riga, the bishop of Dorpat, the king of Denmark, the Dominican and Franciscan orders, and the Grand Master of the Teutonic Order assembled at Vilnius, when Gedymin confirmed his promises and undertook to be baptized as soon as the papal legates arrived. A compact was then signed at Vilnius, in the name of the whole Christian World, between Gedymin and the delegates, confirming the promised privileges.
But the christianizing of Lithuania was by no means to the liking of the Teutonic Knights, and they used every effort to nullify Gedymin's far-reaching design. This, unfortunately, it was easy to do. Gedymin's chief object was to save Lithuania from destruction at the hands of the Germans. But he was still a pagan reigning over semi-pagan lands; he was equally bound to his pagan kinsmen in Samogitia, to his Orthodox subjects in Belarus, and to his Catholic allies in Masovia. His policy, therefore, was necessarily tentative and ambiguous, and, might very readily be misinterpreted.
Thus his raid upon Dobrzyn, the latest acquisition of the knights on Polish soil, speedily gave them a ready weapon against him. The Prussian bishops, who were devoted to the knights, at a synod at Elbing questioned the authority of Gedymin's letters and denounced him as an enemy of the faith; his Orthodox subjects reproached him with leaning towards the Latin heresy; while the pagan Lithuanians accused him of abandoning the ancient gods. Gediminas disentangled himself from his difficulties by repudiating his former promises; by refusing to receive the papal legates who arrived at Riga in September 1323; and by dismissing the Franciscans from his territories. These apparently retrogressive measures simply amounted to a statesmanlike recognition of the fact that the pagan element was still the strongest force in Lithuania, and could not yet be dispensed with in the coming struggle for nationality.
At the same time Gedymin through his ambassadors privately informed the papal legates at Riga that his difficult position, compelled him for a time to postpone his steadfast resolve of being baptized, and the legates showed their confidence in him by forbidding the neighboring states to war against Lithuania for the next four years, besides ratifying the treaty made between Gediminas and the archbishop of Riga. Nevertheless in 1325 the Order, disregarding the censures of the church, resumed the war with Gediminas, who had in the meantime improved his position by an alliance with Wladislaus Lokietek, king of Poland, whose son Casimir now married Gedymin's daughter Aldona.
Incorporation of Slavic lands
While on his guard against his northern foes, Gediminas from 1316 to 1340 was aggrandizing himself at the expense of the numerous Slavonic principalities in the south and east, whose incessant conflicts with each other wrought the ruin of them all. Here Gedymin's triumphal progress was irresistible; but the various stages of it are impossible to follow, the sources of its history being few and conflicting, and the date of every salient event exceedingly doubtful. One of his most important territorial accretions, the principality of Halych-Volynia; was obtained by the marriage of his son Lubart with the daughter of the Galician prince; the other, Kiev, apparently by conquest.
While exploiting Slavic weakness in the wake of the Mongol invasion, Gediminas wisely avoided war with the Golden Horde, a great regional power at the time, while expanding Lithuania's border towards the Black Sea. He also secured an alliance with the nascent grand duchy of Muscovy by marrying his daughter, Anastasia, to the grand duke Simeon. But he was strong enough to counterpoise the influence of Muscovy in northern Russia, and assisted the republic of Pskov, which acknowledged his overlordship, to break away from Great Novgorod.
His internal administration bears all the marks of a wise ruler. He protected the Catholic as well as the Orthodox clergy, encouraging them both to civilize his subjects; he raised the Lithuanian army to the highest state of efficiency then attainable; defended his borders with a chain of strong fortresses; and built numerous towns including Vilnius, the capital (first mentioned ca 1321). At first he moved the capital city to the newly built city of Trakai, but in 1323 re-established a permanent capital in Vilnius, on the site of the capital of King Mindaugas, formerly called Voruta.
Gedymin died in the winter of 1342 of a wound received at the siege of Bayerburg castle. He was married three times, and left seven sons and six daughters. Two of his sons perished in battle. Jaunutis initially ruled Vilnius after the death of his father and was formally Grand Duke of Lithuania until his elder brothers Algirdas and Kęstutis returned from military campaigns in Ruthenia and forced him to abdicate his throne in their favor.
Lest anyone think that Europeans were converted to Christianity by peaceful methods like reason and kindness, they were nearly all converted at the point of the sword (by the various Roman Catholic Military Orders), or by being forced to after their leader/King chose to convert. Gediminas tried to placate the war-mongering Christians by allowing them into his country and treating them as equals, like any decent human does. But, alas, it didn't work, and the Christians invaded anyway. Ho hum.