Second passage is vastly superior.
btw, reading these two side-by-side, I'm wondering whether excessive summarization automatically leads to "disordered topic" progression....(or whatever it should be called).
In the older passage, the grammatical subjects of the sentences inside a paragraph are often the same.
In the new passage, a paragraph can have almost as many different subjects as it does main clauses.
Make the TOPIC of the paragraph the GRAMMATICAL SUBJECT of most (not necessarily all) of the MAIN CLAUSES in that paragraph.
The more I think about it, the more I think that compression makes cohesion much more challenging & difficult to achieve.
Frederick I was the first ruler to call his lands the Holy Roman Empire.
However this region was actually a patchwork of feudal territories.
His forceful personality and military skills enabled him to dominate the German princes, yet whenever he left the country, disorder returned.
Following Otto’s example, Frederick repeatedly invaded the rich cities of Italy.
His brutal tactics spurred Italian merchants to unite against him.
He also angered the Pope, who joined the merchants in an alliance called the Lombard League.
I'm pretty sure that the difference in readability stems from the difference in cohesion.
1. Frederick I
2. this region (from end of preceding sentence)
3. His forceful personality and military skills
5. His brutal tactics
6 MAIN CLAUSES
5 GRAMMATICAL SUBJECTS are "Frederick" or something belonging to Frederick (e.g.: "his forceful personality")
1 GRAMMATICAL SUBJECT follows directly from the end of the preceding sentence:
Frederick I was the first ruler to call HIS LANDS the Holy Roman Empire.
However THIS REGION was actually a patchwork of feudal territories.
I'm not aware of a scale for measuring the cohesiveness of a passage, but if one exists it would show that the older text has high cohesion while the MacDougal Littell text has low cohesion.