Both in the case of the edict of toleration by Galerius and that by Constantine and Licinius, the original Latin text is to be found in Lactantius, and merely a Greek translation in Eusebius, (H. E., Bk. VIII, 17, and X, 5).

EDICT OF TOLERATION BY GALERIUS – 311 A. D.

Lactantius,  Opera, ed. O. F. Fritzsche, II, P. 273. (Bibl. Patt. Ecc. Lat. XI, Leipzig, 1844.)

Lactantius De mortibus persecutorum 33.11   ...Et iam deficiens edictum misit huiusmodi:

34 "Inter cetera quae pro rei publicae semper commodis atque utilitate disponimus, nos quidem volueramus antehac iuxta leges veteres et publicam disciplinam Romanorum cuncta corrigere atque id providere, ut etiam Christiani, qui parentum suorum reliquerant sectam, ad bonas mentes redirent, 2 siquidem quadam ratione tanta eosdem Christianos voluntas invasisset et tanta stulti tia occupasset, ut non illa veterum instituta sequerentur, quae forsitan primum parentas eorundem constituerant, sed pro arbitrio suo atque ut isdem erat libitum, ita sibimet leges facerent quas observarent, et per diversa varios populos congregarent. 3 Denique cum eiusmodi nostra iussio extitisset, ut ad veterum se instituta conferrent, multi periculo subiugati, multi etiam deturbati sunt. 4 Atque cum plurimi in proposito perseverarent ac videremus nec diis eosdem cultum ac religionem debitam exhibere nec Christianorum deum observare, contemplatione mitissimae nostrae clementiae intuentes et consuetudinem sempiternam, qua solemus cunctis hominibus veniam indulgere, promptissimam in his quoque indulgentiam nostram credidimus porrigendam. Ut denuo sint Chrsitiani et conventicula sua componant, ita ut ne quid contra disciplinam agant. 5 <Per> aliam autem epistolam iudicibus significaturi sumus quid debeant observare. Unde iuxta hanc indulgentiam nostram debebunt deum suum orare pro salute nostra et rei publicae ac sua, ut undique versum res publica praestetur incolumis et securi vivere in sedibus suis possint."

35 Hoc edictum proponitur Nicomediae pridie Kalendas Maias ipso octies et Maximino iterum consulibus.

Translation:

(34.) Among other arrangements which we are always accustomed to make for the prosperity and welfare of the republic, we had desired formerly to bring all things into harmony with the ancient laws and public order of the Romans, and to provide that even the Christians who had left the religion of their fathers should come back to reason ; since, indeed, the Christians themselves, for some reason, had followed such a caprice and had fallen into such a folly that they would not obey the institutes of antiquity, which perchance their own ancestors had first established; but at their own will and pleasure, they would thus make laws unto themselves which they should observe and would collect various peoples in diverse places in congregations. Finally when our law had been promulgated to the effect that they should conform to the institutes of antiquity, many were subdued by the fear of danger, many even suffered death. And yet since most of them persevered in their determination, and we saw that they neither paid the reverence and awe due to the gods nor worshipped the God of the Christians, in view of our most mild clemency and the constant habit by which we are accustomed to grant indulgence to all, we thought that we ought to grant our most prompt indulgence also to these, so that they may again be Christians and may hold their conventicles, provided they do nothing contrary to good order. But we shall tell the magistrates in another letter what they ought to do.

Wherefore, for this our indulgence, they ought to pray to their God for our safety, for that of the republic, and for their own, that the republic may continue uninjured on every side, and that they may be able to live securely in their homes.

(35)This edict is published at Nicomedia on the day before the Kalends of May, in our eighth consulship and the second of Maximinus.

THE "EDICT OF MILAN" - 313 A. D.

Lactantius, Opera, ed. O. F. Fritzsche, II, p 288-9. (Bibl Patr. Ecc. Lat. XI).

Lactantius De mortibus persecutorum 48:

Licinius vero accepta exercitus parte ac distributa traiecit exercitum in Bithyniam paucis post pugnam diebus et Nicomediam ingressus gratiam deo, cuius auxilio vicerat, retulit ac die Iduum Iuniarum Constantino atque ipso ter consulibus de resituenda ecclesia huius modi litteras ad praesidem datas proponi iussit:

2 »Cum feliciter tam ego [quam] Constantinus Augustus quam etiam ego Licinius Augustus apud Mediolanum cinvenissemus atque universa quae ad commoda et securitatem publicam pertinerent, in tractatu haberemus, haec inter cetera quae videbamus pluribus hominibus profutura, vel in primis ordinanda esse credidimus, quibus divinitatis reverentia continebatur, ut daremus et Christianis et omnibus liberam potestatem sequendi religionem quam quisque voluisset, quod quicquid <est> divinitatis in sede caelesti. Nobis atque omnibus qui sub potestate nostra sunt constituti, placatum ac propitium possit existere. 3 Itaque hoc consilium salubri ac reticissi ma ratione ineundum esse credidimus, ut nulli omnino facultatem abnegendam putaremus, qui vel observationi Christianorum vel ei religioni mentem suam dederet quam ipse sibi aptissimam esse sentiret, ut possit nobis summa divinitas, cuius religioni liberis mentibus obsequimur, in omnibus solitum favorem suum benivolentiamque praestare. 4 Quare scire dicationem tuam convenit placuisse nobis, ut amotis omnibus omnino condicionibus quae prius scriptis ad officium tuum datis super Christianorum nomine <continebantur, et quae prorsus sinistra et a nostra clementia aliena esse> videbantur, <ea removeantur. Et> nunc libere ac simpliciter unus quisque eorum, qui eandem observandae religionis Christianorum gerunt voluntatem. Citra ullam inquietudinem ac molestiam sui id ipsum observare contendant. 5 Quae sollicitudini tuae plenissime significanda esse credidimus, quo scires nos liberam atque absolutam colendae religionis suae facultatem isdem Christianis dedisse. 6 Quod cum isdem a nobis indultum esse pervideas, intellegit dicatio tua etiam aliis religionis suae vel observantiae potestatem similiter apertam et liberam pro quiete temporis nostri <esse> concessam, ut in colendo quod quisque delegerit, habeat liberam facultatem. <Quod a nobis factum est. Ut neque cuiquam> honori neque cuiquam religioni <detrac tum> aliquid a nobis <videatur>. 7 Atque hoc insuper in persona Christianorum statuendum esse censuimus, quod, si eadem loca, ad quae antea convenire consuerant, de quibus etiam datis ad officium tuum litteris certa antehac forma fuerat comprehensa. Priore tempore aliqui vel a fisco nostro vel ab alio quocumque videntur esse mercati, eadem Christianis sine pecunia et sine ulla pretii petitione, postposita omni frustratione atque ambiguitate restituant; qui etiam dono fuerunt consecuti, eadem similiter isdem Christianis quantocius reddant, etiam vel hi qui emerunt vel qui dono fuerunt consecuti, si petiverint de nostra benivolentia aliquid, vicarium postulent, quo et ipsis per nostram clementiam consulatur. Quae omnia corpori Christianorum protinus per intercessionem tuam ac sine mora tradi oportebit. 9 Et quoniam idem Christiani non [in] ea loca tantum ad quae convenire consuerunt, sed alia etiam habuisse noscuntur ad ius corporis eorum id est ecclesiarum, non hominum singulorum, pertinentia, ea omnia lege quam superius comprehendimus, citra ullam prorsus ambiguitatem vel controversiam isdem Christianis id est corpori et conventiculis eorum reddi iubebis, supra dicta scilicet ratione servata, ut ii qui eadem sine pretio sicut diximus restituant, indemnitatem de nostra benivolentia sperent. 10 In quibus omni bus supra dicto corpori Christianorum intercessionem tuam efficacissimam exhibere debebis, ut praeceptum nostrum quantocius compleatur, quo etiam in hoc per clementiam nostram quieti publicae consulatur. 11 Hactenus fiet, ut, sicut superius comprehensum est, divinus iuxta nos favor, quem in tantis sumus rebus experti, per omne tempus prospere successibus nostris cum beatitudine publica perseveret. 12 Ut autem huius sanctionis <et> benivolentiae nostrae forma ad omnium possit pervenire notitiam, prolata programmate tuo haec scripta et ubique proponere et ad omnium scientiam te perferre conveniet, ut huius nostrae benivolentiae [nostrae] sanctio latere non possit."

13 His litteris propositis etiam verbo hortatus est, ut conventicula <in> statum pristinum red derentur. Sic ab eversa ecclesia usque ad restitutam fuerunt anni decem, menses plus minus quattuor.

Translation:

When I, Constantine Augustus, as well as I Licinius Augustus d fortunately met near Mediolanurn (Milan), and were considering everything that pertained to the public welfare and security, we thought -, among other things which we saw would be for the good of many, those regulations pertaining to the reverence of the Divinity ought certainly to be made first, so that we might grant to the Christians and others full authority to observe that religion which each preferred; whence any Divinity whatsoever in the seat of the heavens may be propitious and kindly disposed to us and all who are placed under our rule And thus by this wholesome counsel and most upright provision we thought to arrange that no one whatsoever should be denied the opportunity to give his heart to the observance of the Christian religion, of that religion which he should think best for himself, so that the Supreme Deity, to whose worship we freely yield our hearts) may show in all things His usual favor and benevolence. Therefore, your Worship should know that it has pleased us to remove all conditions whatsoever, which were in the rescripts formerly given to you officially, concerning the Christians and now any one of these who wishes to observe Christian religion may do so freely and openly, without molestation. We thought it fit to commend these things most fully to your care that you may know that we have given to those Christians free and unrestricted opportunity of religious worship. When you see that this has been granted to them by us, your Worship will know that we have also conceded to other religions the right of open and free observance of their worship for the sake of the peace of our times, that each one may have the free opportunity to worship as he pleases ; this regulation is made we that we may not seem to detract from any dignity or any religion.

Moreover, in the case of the Christians especially we esteemed it best to order that if it happems anyone heretofore has bought from our treasury from anyone whatsoever, those places where they were previously accustomed to assemble, concerning which a certain decree had been made and a letter sent to you officially, the same shall be restored to the Christians without payment or any claim of recompense and without any kind of fraud or deception, Those, moreover, who have obtained the same by gift, are likewise to return them at once to the Christians. Besides, both those who have purchased and those who have secured them by gift, are to appeal to the vicar if they seek any recompense from our bounty, that they may be cared for through our clemency,. All this property ought to be delivered at once to the community of the Christians through your intercession, and without delay. And since these Christians are known to have possessed not only those places in which they were accustomed to assemble, but also other property, namely the churches, belonging to them as a corporation and not as individuals, all these things which we have included under the above law, you will order to be restored, without any hesitation or controversy at all, to these Christians, that is to say to the corporations and their conventicles: providing, of course, that the above arrangements be followed so that those who return the same without payment, as we have said, may hope for an indemnity from our bounty. In all these circumstances you ought to tender your most efficacious intervention to the community of the Christians, that our command may be carried into effect as quickly as possible, whereby, moreover, through our clemency, public order may be secured. Let this be done so that, as we have said above, Divine favor towards us, which, under the most important circumstances we have already experienced, may, for all time, preserve and prosper our successes together with the good of the state. Moreover, in order that the statement of this decree of our good will may come to the notice of all, this rescript, published by your decree, shall be announced everywhere and brought to the knowledge of all, so that the decree of this, our benevolence, cannot be concealed.

Both texts translated in University of Pennsylvania. Dept. of History: Translations and Reprints from the Original Sources of European history, (Philadelphia, University of Pennsylvania Press [1897?-1907?]), Vol 4:, 1, pp. 28-30 . The text of the translation submited from Internet Medieval Source Book.