How much of the world did European empires actually occupy in the 19th century?

Before the 19th century, European empires were to a large extent based on coastal trade outposts and islands, and European power projection overseas was limited to the navies that linked these. If we look at maps of European empires in the 18th century, they were mostly coastal possessions around the world, with very little actual penetration into the hearts of the continents.<br><br>But during the 19th century, much of the world came under direct occupation and the colonial map became more similar to what it was in 1914.<br><br>What was it that in the 19th century allowed Europeans to conquer new areas of the world at an unprecedented pace?<br><br>Was it the invention of the machine gun and the Gatling gun, which allowed Europeans to reliably defeat non-Europeans in pitched battles?<br><br>Or was it the steamship? Railways? The telegraph? Conquistador tactics?