When the Fathers say the Holy Ghost proceeds from the Father "through the Son," is that the same as the Filioque?

Yes. "Through the Son" is the Filioque in the older patristic idiom. Filioque means "and from the Son," and the Latin word for procession allows the Son to be the point through which the Spirit proceeds from the Father. Yes, that is what it means. Filius is Latin for "son," and Filioque is the ablative form with the conjunction attached, so the clause in the Creed says the Holy Spirit proceeds "from the Father and the Son." When a Father says the Spirit proceeds from the Father through the Son, he is teaching the same reality, only with the order of origin made explicit: the Father is the fountainhead, and the Son is not excluded from the spiration. The two phrasings can say one thing because of a point of vocabulary most people never hear. That is where the thousand year quarrel actually lives. Greek theology from the fourth century onward used the verb ekporeuesthai for the Spirit's procession, and that verb means procession from an original source. If you take that word and say the Spirit "ekporeuetai" from the Father and the Son, you have said there are two original sources in God, and that would in fact be heretical. The Latin verb the Church used, procedere, does not carry that restriction. Procedere can include an intermediary point, which is the Son. So the Filioque as the Latin Church has always stated it never meant two fountainheads. The Second Council of Lyons in 1274 said this in so many words: the Holy Spirit proceeds eternally from the Father and the Son, "not as from two beginnings, but from one beginning, not from two breathings but from one breathing" (Denzinger 460). That is precisely what "through the Son" protects. So the doctrine is not a Latin novelty. Pope St. Leo I held it as dogma in 447, and it stands behind Chalcedon in 451. The Athanasian Creed states flatly that the Holy Spirit "is not made nor created nor generated but proceeds from the Father and the Son." It was inserted into the Nicene Creed at the Council of Toledo in 589. Lateran IV repeats it (Denz. 428), Lyons II defines it, and the Council of Florence in 1438 reinforced it (Denz. 691, 703). St. Thomas treats it under the term "spiration" in the Summa (I, Q. 27, aa. 3 to 4, and QQ. 36 to 38), and the Catechism of the Council of Trent says the Spirit proceeds from the divine will inflamed, as it were, with love (I, 9, 7). Scripture supports it, though not as loudly as we would like, and I say that honestly. John 15:26 says the Spirit of truth "proceeds from the Father," and it does not mention the Son. But Romans 8:9 calls the same Spirit "the Spirit of Christ," an objective genitive, and that verse is a decisive commentary on John 15:26. Add John 14:16 and 16:7, where the Son sends the Spirit, John 20:22, where He breathes Him on the Apostles, Galatians 4:6, and Philippians 1:19. Whoever sends the Spirit as His own is a principle of the Spirit's procession. Where I will grant the Orthodox something is this: the particular Greek verb of John 15:26 is never used of the Son, and if you rest the whole argument on that one word you have a decent objection. That is why the Latins can use a different and closer Greek equivalent, proienai, which matches procedere and has the room that ekporeuesthai does not. Stated that way the Filioque stands, and the Father is still confessed as the sole fountainhead without the Son being written out of the Spirit's origin. That is the honest ground for a reconciliation, and the 1995 Vatican statement on the Greek and Latin traditions regarding the procession of the Holy Spirit was moving in that direction. But be clear about the history. The Eastern churches broke off in 1054 holding that the Spirit proceeds from the Father only. Most of the Latin Fathers, Augustine above all, taught the Filioque; the Eastern Fathers were mostly silent or equivocal on it, which is exactly why their "through the Son" language is a witness for us and not against us. Weigh the popes and councils that actually dealt with the question. The Catholic decision holds.