Elizabeth died in 1603, leading to the Union of the Crowns. This meant that the same person held the crowns of England, Scotland, and Ireland, and ruled them jointly as a monarch. The actual union of the two kingdoms, Scotland and England, into one occurred in 1707 through acts of Parliament. Conquest is typically justified and executed through force. The assumption of the crown of England by James was remarkable because of how peaceful the transition of power was. The most often quoted source on this was the diary of John Manning, who was living in London at the time. He wrote that "the proclamacion [of the new king] was heard with greate expectacion and silent joye...at night they shewed it by bonefires, and ringing [bells]. Noe tumult, noe contradicion, noe disorder in the city; every man went about his busines, as readylie, as peaceably, as securely, as though there had bun noe change...God be thanked, our king hath his right!"

No. The word "conquer" in English has a specific meaning of military invasion, for one thing.

It's something of a common misconception that the accession of James VI of Scotland to the throne of England in 1603 was the point at which the two countries united.

In fact, it simply meant that one man was now king of two different places. Both kept their own parliament, currency, flags etc. In fact, James did try and proclaim himself to be "King of Great Britain" and tried to unify the two countries but neither Parliament wanted it. The English didn't want the Scottish poor heading south and stealing jobs, the Scots feared they'd just end up as an English province.

It wasn't until a century later in 1707 that the two parliaments were united and the Kingdom of Great Britain officially created.