I see you ignited quite a discussion! I'll simply interpret this as you choosing to play the devil's advocate, for the sake of the argument... I've seen a number of students facing exams do this, for practice.
War is Necessary for Certain Reasons
Some say that war is "a necessary evil". Others say that war can be avoided by using peaceful means. I think that war is a necessary evil for three reasons.
In proper English, numbers are written fully as words.
First, you would go to war if another country attacked you. Let us imagine, if another country attacks you for some reason, and peace cannot solve the problem, then war is necessary.
First sentence: use the second conditional to keep your argument calm and hypothetical. You used first conditional, which tells me you think war is a very real and likely event.
Second, countries will go to war over some serious disagreement that needs to be resolved. For example, these days China and Japan have a disagreement over the Diao Yu Island. If this argument can't be resolved within a certain period of time, war will probably occur between these two countries.
Next, if a country was attacked by another country, and you wanted to help that country, you would go to war. For instance, America and England are allies. If America needed to resolve certain problems through war, England would want to help them. So, England would join America.
Again, you need the second conditional here. Consider the <em>actual likelihood</em> of it happening (not the logical cause-and-effect). Learn to use the second conditional properly; it's incredibly useful. :)
In fact, every war needs to achieve some purpose. There might be a political purpose, an economic purpose, or some military purpose. Each war needs many soldiers, weapons, and resources.
I changed the last word to keep consistent; you mixed countable and uncountable nouns, which caused confusion in your grammar.
Also, pay attention to punctuation. A space does not go before a comma or full stop.
True, war is very harmful to citizens. Many people have died in wars. So, we don't want war, but sometimes we must have it. If another country attacked, if we needed to resolve a serious issue, or if another country needed help, maybe we might go to war.
Why did I add <em>true</em>? :) To make the last paragraph sound more like a conclusion. Without it, it sounds as if you were making a new point.
There are a number of typical phrases to use when structuring a speech, so it's useful to know them well - especially those phrases which begin a paragraph.
Good effort.
Some Reasons of what War is Necessary for Some Reasons
Some say It is said that war is "a necessary evil necessary". Others sayOtherwise that war can be avoided by using peaceful means . I think that there are 3 reasons of what war is a necessary evil necessary for 3 reasons.
First, you will go to in war if another country attacks youyours . Let us imagine, if another country attacks you for some reason on any excuse while peace cannot couldn't solve the problem; war is necessary.
Second, countries will go to war be warring for as some serious disagreement that needs to be resolved . For example, these days China and Japan have a disagreement about the Diao Yu Island. If this argument can't be resolved during a period of time, war will probably occur between these two countries.
Next, if a country is attacked by another country, and you want to help that country, you will go to war. For instance, America and England are good friends . If America needs to resolve some problems by war, England will want to help them. So, England will join in America.
In fact, every war needs to be achieve some purpose . There might be a political purpose , economic purpose, or some military purpose. Each war needs a lot of soldiers, weapons, and money.
War is very harmful to citizens . Many people died in wars. So, we don't want war ,but sometimes we must have war . If another country attacks come, if we need to resolve a serious issue ,or if another country needs help ,maybe we might go to war.
