L21 is a new marker (first identified about one year ago). Scientific studies take time to be peer-reviewed and published. At present the evidence about the spread of R1b-L21 comes from commercial testing. The biggest collection of results about L21 that I know is FTDNA R-L21 Project (424 results to this day). You will see on the map that most of the L21 tested so far cluster around Germany and the British Isles. Except one person in Croatia and one in Romania, there are no L21 in south-east Europe, and none in the Middle East or North Africa.
The situation in the Americas was different from Europe. In the last 1000 years, soldiers inside Europe just didn't kill men in conquered territory and rape their women or take them as wives. European societies were too mutually similar for this to happen.
In my example about crusaders, they had no interest in killing or raping other Europeans. They were the first pan-European army. Their enemies were the Muslims, not other Christians. If they did conceive bastards within Europe, it was probably with consenting women, like prostitutes.
From the Renaissance onwards, European fought for their sovereign and country. They were part of well organised armies and just followed orders. Rapes or local women did occasionally occur, but were often punished by military officers (Napoleon is known to have executed some of his own soldiers for raping locals in Austria and Germany).
Conquistadors were far from home and did pretty much what they wanted. Their own government had little control on them. Many of them were outlaws in their own country. Even Hernan Cortes was being pursued by the Spanish army in Cuba when he arrived in Mexico. He would have been imprisoned or executed had he not managed the incredible feat of overthrowing the Aztec government.
Conquered Amerindians were not Christian at first, which gave the colonisers an excuse to kill or rape them at whim.
