The Wars of the Roses (1455-1485) is the term that is used to describe a period of war between two houses the House of Lancaster and the House of York (Lancaster and York are counties in the North of England).
The reason for the conflict was the fact that both of these houses wanted to rule the country.
The War of the Roses was a civil war.
It lasted around thirty years but was more destructive for England than the Hundred Years War (this was because in the War of the Roses all the battles took place in England, and during the Hundred Years' War a lot of fighting happened in France. This means that there was a lot more loss of life in the English ranks in the War of the Roses.).
One of the families consisted of descendants of Edward III and the other of Henry IV. Both thought they were the rightful heirs to the throne.
The king at the time - King Richard II died without an heir. He was overthrown and killed by Henry IV (Henry Bolingbroke, who was a part of House of Lancaster). Henry's supporters were a group that were the Lancastrian faction. Their opponents, the House of York (family descended from Edward III) and their supporters were called the Yorkist faction.
The name of this period and the association with the roses came later, when the wars had ended. The reason is the fact that the symbol of the House of York was a white rose and the House of Lancaster was a red rose in Renaissance literature, during Shakespeare's days. This is even mentioned in one of Shakespeare's plays, 'Henry VI'.
The roses were not officially on the Houses' coats of arms, but have a strong association with them. The servants of the houses used to wear uniforms which had white or red roses on them.
So how did it begin?
The war began in 1455 when Richard, Duke of York started to question the current king's right to the throne.The king at the time was the Lancastrian Henry VI, a very religious but not very strong leader who had some mental health problems. (He was related to Henry IV, the "hero" in Shakespeare's play Richard II.).Richard Duke of York's argument was that the relatives of Henry VI did not have any right to take the throne because Henry did not become king in the proper and legal way.Richard's son Edward becomes King Edward IV in 1461 and Henry VI leaves the country for nine years.
Edward IV ruled happily without many problems until 1470, when Henry VI returned with an army. Henry VI managed to get his position as king back for a short period of time, but then Edward took it away from him again.
Edward IV died in 1483, and his son Edward V was the next Yorkist ruler was the supposed to become the next king. Even though Edward V was unusually mature and capable and older than his years - he was still a child. His uncle Richard, Duke of Gloucester made himself regent (temporary King) until the boy grew up. After doing so, Richard made sure he was in charge of some important laws, including the martial law. Richard was evidently not a very nice man, because he sent young Edward and his younger brother to the Tower of London (he said it was for their 'protection') which is when they mysteriously disappeared. Most people say they were killed.
Richard then made himself King Richard III as he was the next Yorkist in line for the throne. There were no other candidates. King Richard's rule as king had problems with the house of Lancaster. He had a lot of support from the northern part of England, but the southerners were very displeased with the supposed killing of the two young princes in the Tower of London. The house of Lancaster was one of the fractions that attacked Richard.
The fighting stopped suddenly at the Battle of Bosworth Field in 1485 when the Lancastrian faction won the deciding battle. Henry Tudor, a prince from Wales gathered an army to fight against Richard III. The Tudors were related to the House of Lancaster, and Henry Tudor was a strong candidate for the position of king because most of the major Lancastrian and Yorkist candidates had killed each other during the thirty years of warfare. Henry Tudor proclaimed himself King Henry VII. In the first few years of his reign, he got rid of all of his competitors. He then married Edward IV's daughter Elizabeth to make sure his child will have good chances of becoming the next king. The marriage was a very clever political move: he had a clear right to the throne through his father (from Lancashire) and she did too, through her mother (from Yorkshire). So, Henry VII's children would have both Yorkist and Lancastrian blood. Their son became Henry VIII, who was the father of queen Elizabeth I, monarch who ruled during Shakespeare's early career.