It would seem that in the wars that were fought to contain Communism -- Korea, Viet Nam, many "brushfire" incidences such as the raid on the island of Granada -- the idea of spreading their ideology was not nearly as important to the Communists as just spreading, having more and more land under their control.
China has been a somewhat different story. The repression and brutality of Stalinism appeared the same but the Chinese actually seem to be trying to find ways to make Communism actually improve their country and way of life. Of course, in both major proponents of the philosophy, there is a ruling elite that just like the Emperor and the Czar get the most and best of everything.
The democracies fought to keep Communism from expanding but it doesn't appear it was actually motivated by political considerations. In most of the countries where the democracies have military bases and such, the local governments are left to their own choices even if they are repressive regimes. It appears that most wars that have been fought, including, WWI and WWII, had some other basis, some other foundation. It would seem that land acquisition and the need for greater and greater economic input are far more likely to be the root of wars.
The most noticeable residual effect of events from the middle of the twentieth century is the re-emergence of Islam as a power in the world. In the Middle Ages, Islam and the countries where it was the major factor of life, was one of the great powers. People look at the third world countries now represented by this religion and don't realize, for the most part, that there was a point in history where learning and civilization were kept alive by the Arab states. When the Crusaders invaded the Middle East to "rescue" the Holy Land from the "infidels," they found people who believed in bathing regularly and had the learning from earlier civilizations preserved. Eventually, these countries slipped into ignorance and became the nations we see today that Euro-based nations make fun of and use disparaging terms such as "camel jockeys" of.
It appears, if one takes a long view of the last fifty years, that the establishment of the Jewish state awoke the Arab/Islamic nations and peoples and unified them in a way nothing else had in centuries. Does Islam qualify as a political ideology? I think one would have to say it does and it is an ideology that controls the thinking of millions of people not only in the Arab world but across much of Asia as well. Is there an economic aspect or impact that has world-wide significance to Islam? As much of the world's oil supply is located in Arab/Islamic controlled territories one would have to say yes.
Today, as one looks at the world, it seems as if political ideologies, whether, they are secular or inspired by a religion aren't the real power that moves world events. It appears that economics and technology are the driving forces behind what is happening in the world. One country after another has developed nuclear capability, each one with the idea that they must have this ability to protect themselves. It is the strangest idea of self-protection that a weapon that makes the land unusable is a way of defense. To go along with nuclear weapons, these countries must either buy or develop the means to deliver their "defensive" capability. This means rockets. To go with rockets the countries need the facilities for launching and guiding the missiles.
Another totally different and new technology that is important in the world is communication technologies; satellites, and the Internet make us very close to one world in spite of differences in world view.
Besides, technology, trade on a world-wide basis, is perhaps the most powerful mover of world events and policies. Countries with large populations of people willing to work for what Americans and Western Europeans consider starvation wages, are beginning to show up on the world stage in very different ways than previously.
So, as one looks at the world today, one sees the Chinese as an up and coming power, not because of communism but because they have a huge pool of intelligent, highly motivated workers who consider themselves done well by to work for perhaps a tenth of what an American or European would expect for the same work. In an issue of a Sunday magazine supplement published a few years ago, there was a story of a young Chinese woman who worked in a factory that makes bras for the Western markets. Although what she made a day would seem like practical slavery to Western workers, she considered herself well-paid and up and coming. Her wages allowed her own little apartment that she didn't have to share, and to purchase a motor scooter. Yes, she considered herself very well-paid.
In summary, it would seem that the face of nationalism has changed dramatically over the last fifty years. There are many little countries that are demanding to be recognized along ancient lines of boundaries, ethnicity, language and religion. These countries are frequently in conflict with the larger powers such as the previous Soviet Union and with each other. This keeps a certain level of turmoil going in the world. Then there is the uniting and reemergence of Islam as a force on the world scene. These changes are mostly the results of occurrences in the middle of the twentieth century.
Technology has been a major force for change around the world. Military technology has been important in that it has spurred increased scientific growth even in what are considered backward, third world countries. Military technology such as rocketry has also led to the space race and actual exploration off-planet beginning. As the technology for the military and space exploration has grown, it has spun off amazing new technologies for civilian life such as microwave ovens and personal computers.
World trade changes have caused and are continuing to cause powerful changes in where power rests and grows in the world. As western businesses continue to seek sources of cheap labor and places where the restrictions on land usage and pollution are lax or non-existent, trade balances change in favor of previously poverty-stricken nations. As economics change, so does the balance of power.
How did this particular theme impact the development of civilization as it was then and is now? What was its role in shaping civilization in the west?