I want to know the answer to the following question:
In what year did the three original  cantons join with five other cantons to form the "Old Confederacy" of eight states?
All the background I'm provided with is that "By 1460, the confederates controlled most of the territory south and west of the Rhine to the Alps and the Jura mountains, particularly after victories against the Habsburgs (Battle of Sempach, Battle of Näfels), over Charles the Bold of Burgundy during the 1470s, and the success of the Swiss mercenaries.". Is that enough to answer the question?
Answer: no