The schism over the date of the observance of the last supper was the first major schism (mid 2nd century CE) and it actually divided the eastern (quartodecimans/polycarp) and western churches (Roman/Victor). Note that some sources claim the disagreement was over the date of observance of Easter - but this is false information. Those who followed the apostolic/Biblical practice observed the last supper on passover (pascha(l)) night and had nothing to do with the later observance of the pagan holiday of Easter. The Bible clearly shows Jesus observed the last supper on passover night which only rarely falls on a Sunday on our calendar. [probability: 1 in 7]
The schism over the date of the observance of the last supper may be important to your church but it certainly wasn't the first major schism. That appeared in the first decades after Jesus' death and hinged on whether converts to Christianity first had to become Jews. I believe James and his followers in Jerusalem insisted they did, others, like Paul, disagreed. The Romans made the decision by destroying Temple and enslaving the Jews there. Paul won by default and Christianity spread throughout the pagan Roman world. Had he lost, Christianity would be a minor Jewish cult and probably have disappeared.
It was the governing body in Jerusalem that settled the disagreement over the circumcision issue. And that was not what I meant by schism. Read Acts chapter 15.
Excerpt:
"Now some men came down from Ju·deʹa and began to teach the brothers: “Unless you get circumcised according to the custom of Moses,
+ you cannot be saved.”
2 But after quite a bit of dissension and disputing by Paul and Barʹna·bas with them, it was arranged for Paul, Barʹna·bas, and some of the others to go up to the apostles and elders in Jerusalem
+ regarding this issue.
3 So after being escorted partway by the congregation, these men continued on through both Phoe·niʹcia
+ and Sa·marʹi·a, relating in detail the conversion of people of the nations and bringing great joy to all the brothers.
4 On arriving in Jerusalem, they were kindly received by the congregation and the apostles and the elders, and they related the many things God had done by means of them.
+ 5 But some of those of the sect of the Pharisees who had become believers stood up from their seats and said: “It is necessary to circumcise them and command them to observe the Law of Moses.”
+
6 So the apostles and the elders gathered together to look into this matter.
7 After much intense discussion had taken place, Peter rose and said to them: “Men, brothers, you well know that from early days God made the choice among you that through my mouth people of the nations should hear the word of the good news and believe.
+ 8 And God, who knows the heart,
+ bore witness by giving them the holy spirit,
+ just as he did to us also.
9 And he made no distinction at all between us and them,
+ but purified their hearts by faith.
+.....
After they finished speaking, James
+ replied: “Men, brothers, hear me.
+ 14 Symʹe·on
+ has related thoroughly how God for the first time turned his attention to the nations to take out of them a people for his name.
+ 15 And with this the words of the Prophets agree, just as it is written:
16 ‘After these things I will return and raise up again the tent of David that is fallen down; I will rebuild its ruins and restore it,
17 so that the men who remain may earnestly seek Jehovah, together with people of all the nations, people who are called by my name, says Jehovah, who is doing these things,
+ 18 known from of old.’
+ 19 Therefore, my decision is not to trouble those from the nations who are turning to God,
+ 20 but to write them to abstain from things polluted by idols,
+ from sexual immorality,
+ from what is strangled, and from blood."
Notice that the governing body in Jerusalem showed Amos 9:11,12 was fulfilled by people of the nations coming in. And it was the pharisees, not Christians as a whole, that were causing the dissension - that was a sect of the Jews.
However, the schism between Polycarp (and the quartodecimans) and Victor (& the Roman churches) was not settled by appeal to Scripture because Victor refused to follow Jesus example of observing on passover night. In fact Victor chose to excommunicate the quartodeciman churches.
The schism is not important to us except as a detail of history. However, the Memorial of Christ's death by observance of the last supper is the only day directed his followers to observe:
Luke 22:19
Also, he took a loaf,
+ gave thanks, broke it, and gave it to them, saying: “This means my body,
+ which is to be given in your behalf.
+ Keep doing this in remembrance of me.”
+
The Memorial is our only holy day and it falls on Nisan 14 (after sundown).