Ben,
No Roman Pontiff ever accused the East of ommitting the Filioque, to my knowledge. However, Charlamange sure did, along with the Frankish Bishops. But the problem is that the EOC says that the Filioque is heretical, if so then Rome and the rest of the Western Church fell to heresy long before the 11th century!
The subject is unfortunately not as simple as this.
The beginning of the
filioque dispute can be found well before it became a contentious issue. While the Eastern Fathers generally were very clear in making a distinction between the "eternal/essential" and "economic" Trinity, the Western Fathers were not. This is not to say you would not find this distinction at all in the Western Fathers - it's just that it was not as clearly taught. St.Gregory Palamas would eventually summarize in a very clear form the teaching of both the Eastern and Western Fathers (or at least the consensus thereof), while preserving all of the careful distinctions involved - he taught that while the Holy Spirit receives His being and proceeds eternally from the Father, He "rests upon" and is manifested through the Son
eternally as well. This teaching is the Patristic consensus (and is unmistakenly the universal teaching of the Eastern Fathers to a man), and while acknowledging an eternal manifestation of the Holy Spirit (and not simply a "temporal" one) from God the Son, is careful to not confuse this with the procession of the Holy Spirit from God the Father. If my understanding of the various modern ecumenical dialogues is correct, it would appear Roman Catholicism is moving towards this understanding of the
filioque, which is obviously a good thing.
Confusion however increases due to three factors. The first, is the unauthorized inclusion of the
filioque clause into the Nicene Creed. Whatever theological justification one wants to use for this insertion, no local Church had the right to do this (this was introduced in Spain, in a misguided attempt to guard against Arianism.) The other early factor was St.Augustine's teaching on the subject. With his greatness, went also an unfortunate tendency to have to explain the "mechanisms" or processes involved in absolutely everything. Thus, he attempted to teach how the "Spiration of the Holy Spirit" differed from the "Begotteness of the Son." The difference he taught, had to do with the fact the Son came from the Father alone, where as the Holy Spirit came from both the Father and the Son. He also taught that the spiration of the Holy Spirit was the mutual love shared between the Father and the Son. All of these explanations were his own, and you don't find them elsewhere in the Fathers.
However, what ended up making this a crisis was the insistance of the Frankish rulers who had political designs upon the Eastern Empire and the Eastern Churches. They were a pretty ignorant bunch, and not only insisted that the Augustinian concept of the
filioque as well as the insertion of the clause belonged in the Nicene Creed, but even claimed that the Eastern Churches had removed it themselves! This was not an unpopular (and false) belief in the west, btw. By the 11th century, it was sufficiently popular that when Cardinal Humbert "excommunicated" the Patriarch of Constantinople, part of the bull of excommunication included the accusation that the East had
removed this clause!
The problem here was that the Franks were Latinophiles (thus not only alienating themselves from the Eastern Fathers who wrote in Greek, but even the many Western Fathers who wrote in Greek before Latin became the common tongue of the west as well), and St.Augustine was certainly the most prolific of the Latin writing/speaking Fathers of the western Church. Thus, the west became "Augustinian" to the point of not reading him within the context which he himself lived. Nor did they seem too keen on taking into account St.Augustine's own caution that many of his ideas were speculative and were to be judged in the future by the Church, or that he had several times retracted opinions he had earlier put forward or otherwise corrected his works (in other words, St.Augustine was humble and did not regard himself as THE authority on any subject, let alone one who would trump all other teachers.)
But the problem is that the EOC says that the Filioque is heretical, if so then Rome and the rest of the Western Church fell to heresy long before the 11th century!
This is a similar argument used by the Roman Catholic party at the Council of Florence - that if a few Fathers had some incorrect ideas on a given subject, they had to be cast out of the Church, and be regarded as heretics. While there is a certain logic to this view on paper, it is very mistaken and not how the Orthodox Church has viewed the subject. I'll do my best to explain why.
What is
heresy? Why is "heresy" bad? Well, the greek word
hairesis refers to the act of
choosing - and in the context of doctrine, this means choosing another way, one's own way of thinking about things, as opposed to the received teachings of the Church.
Why are heresies
bad? Well, since our mind exists in thoughts, how one thinks on a subject can effect how one relates to that subject. A heresy has the potential both of itself, and in terms of it's potential "side effects" (further errors begotten of it) to create road blocks as it were, on the path of salvation. We are not told things about God or His economy for our amusement, or to otherwise satisfy some kind of curiosity on our part (indeed, there is an incredible amount that we do not know, and probably can never know - and all for our own good!), but because obvious God thinks it is important for us to know. The Church's job, as protector and distributor of the Holy Mysteries, is to impart this knowledge to us as it is for our benefit.
The Church guards vigilantly against that very real possibility, that one may so pervert the "road map" that God has given us as it were, that we will not be able to find our way to our destination.
However, we all know that in reality there are going to always be many people (for whatever reason - innocent ignorance due to simplicity, bad circumstances, etc.) who will probably not grasp even many of the basic things of our faith. For example, I do not doubt in the least that if you "quizzed" many Orthodox, you'd find quite a few of them would not immediately grasp (or have been previously aware of) the real difference between the "filioque" teaching on the Trinity as accepted by the Roman Catholics, and the Church's own teaching. At the same time, I would never say such people have forefeitted their salvation because of this simple ignorance or misunderstanding.
But the situation would be different, say if that simple Orthodox person who had unclear or even mistaken views on a subject, were told the truth unambiguously, and willfully decided they "knew better." The same would go for any heirarch who did this (hence why the Church admonishes, then eventually expells clergy who preach heresy "bare headed", and presumably would do this in individual cases of laymen as well.) In that case you have malice, and little visible reason to believe the persons involved simply don't "know any better."
This is not to say
materially believing a wrong/heterox/heretical idea is "ok" or a "good thing" - but it does not have the same weight morally or upon someone's personal salvation that it does after they've been admonished and that heresy becomes
formal on their part. This is another way that heresies become "road blocks" to salvation.
Thus even though there were undoubtedly many prior to the formal schism who had heterodox beliefs about the Holy Trinity, the rest of the Church was either unaware of this, and after becoming aware, was more able to overlook this (to a point) than perhaps many of today's zealots would find tolerable. Yet the Church is able to tolerate much, if it looks as if it's something that can be worked out.
This is also why (despite teaching incorrectly on this subject, and some exagerations on the doctrine of grace) the Fathers of later ages (and contemporary to him) were able to accept St.Augustine as both Orthodox and as a teacher of great repute - because they saw an innocence and humility in his imprecisions/error, and because he did not hold tenaciously to these errors in spite of admonishment.
Unfortunately,
filioquism did not die on it's own, nor did it's later proponents react well to correction - if anything, they not only
did not repented when shown better, but tried to coerce and abuse their errors down the throats of others! Hence why
eventually those subject to the erring Popes (and obviously the Popes themselves) were expelled from the Church.
One last note - the adoption of the errant form of the
filioque teaching, and it's inclusion into the Nicene Creed by the Roman Pontiffs, did not occur until quite late (early 11th century). In fact at the 8th Imperial Council (numbered as ecumenical, btw. by the Eastern Patriarchs as recently as the 19th century) the Roman Pope (then John VIII) agreed that the teaching was in fact errant, and agreed that the clause itself did not belong in the Creed.