Could you help me change the green one to the form as the red one.

[v0031]

There were many similarities between World War I and World War II.
First, both wars were caused by the efforts of some countries to change the international order and the efforts of other countries to prevent that. For example, Germany wanted more power for itself before both wars and other countries wanted to keep it from having power.
Second, both wars were "total wars" that were won by the side that could manufacture the most weapons.
Another similarity of World War I and World War II is the role the United States played in each war. The United States didn’t join either war when they first started. In World War I, we joined the war after Germany resumed its policy of sinking our merchant ships without warning. In World War II, we joined the war after Japan attacked us at Pearl Harbor. In both wars, we helped the Allies to victory.
Another similarity between WWI and WWII was the use of German u-boats and the use of new weapons never before used.

Additionally, both wars saw a heavy use of propaganda to support war efforts, both at home and in other countries in Europe. For this ,could you show me some examples?
[/i][/color]
Finally, both were wars that ended with victories for the countries that had dominated the world order before the war. In other words, the insurgent countries lost both wars.


I mixed the two passages together. However, I don't feel the conjuctions are
integrated peacefully.

[Kingpoleon]

Thirdly and fourthly can be used, if a bit repetitive.

[v0031]

TKS.

I try to put this

Another similarity of World War I and World War II is the role the United States played in each war. → Third, the role the US played in both wars was alike.

[Kingpoleon]

Thirdly, not third.

[True Federalist (진정한 연방 주의자)]

Thirdly, not third.

He used First and Second, not Firstly and Secondly.   Both the -ly and -ly-less forms are valid as long as one consistently uses the same form for the entire list.