Given the task definition and input, reply with output. This task involves creating answers to complex questions, from a given passage. Answering these questions, typically involve understanding multiple sentences. Make sure that your answer has the same type as the "answer type" mentioned in input. The provided "answer type" can be of any of the following types: "span", "date", "number". A "span" answer is a continuous phrase taken directly from the passage or question. You can directly copy-paste the text from the passage or the question for span type answers. If you find multiple spans, please add them all as a comma separated list. Please restrict each span to five words. A "number" type answer can include a digit specifying an actual value. For "date" type answers, use DD MM YYYY format e.g. 11 Jan 1992. If full date is not available in the passage you can write partial date such as 1992 or Jan 1992. If you find multiple spans, please add them all as a comma separated list. Please restrict each span to five words.

Passage: The intervention of Denmark, Sweden and Poland-Lithuania into Livonia began a period of struggle for control of the Baltic, known contemporaneously as the dominium maris baltici. While the initial war years were characterised by intensive fighting, a period of low-intensity warfare began in 1562 and lasted until 1570 when fighting once more intensified. Denmark, Sweden and to some extent Poland-Lithuania were occupied with the Nordic Seven Years' War taking place in the Western Baltic, but Livonia remained strategically important. In 1562, Denmark and Russia concluded the Treaty of Mozhaysk, respecting each other's claims in Livonia and maintaining amicable relations. In 1564, Sweden and Russia concluded a seven-years truce. Both Ivan IV and Eric XIV showed signs of mental disorder, with Ivan IV turning against part of the Tsardom's nobility and people with the oprichina that began in 1565, leaving Russia in a state of political chaos and civil war.
Question: How many years did the period of low-intensity warfare last?
Answer type: Number
8.