There are a lot of sites dealing with World War Two and the Vietnam War, for instance, where vets swap war stories. There are some on the Revolutionary War and the Civil War, particularly of interest to family history buffs. But there are fewer sites about the Korean War, the Spanish-American War of 1898 or World War One.
In short, history is *hit and miss* on the World Wide Web.
Standard reference sources like the CRC Handbook of Chemistry and Physics (over 1,000 pages long, packed full of data in charts and tables) and Famous First Facts (again, thousands of brief entries) are not going to be found on the Web (or not found without paying for a subscription). It simply would take too much time and effort to upload that much information from a printed source when the books are readily available at local libraries.
The Encyclopaedia Britannica is available on the Web by paid subscription only. Same for the Oxford English Dictionary. On the other hand, quite a few business sites provide some information for free but require paid subscriptions for extensive, detailed information. (Information which cost money to gather and organize often will cost money to obtain, even on the Web.)
Shakespearean plays are available full text on the World Wide Web but you will not find more recent books (the ones still protected by copyright).
The Houston Chronicle may be searched for full text articles back as far as 1985, if you are a paid subscriber of the print Houston Chronicle. But the Web version of the newspaper will not have all of the stories in the print version (because the Chronicle may not have the rights to stories not written by their own staff members but which they may publish in their printed paper) and it will often have more stories than appeared in the printed version (because the printed version did not have enough space available).
I frequently get asked for literary criticism material but, as yet, have found little on the World Wide Web. Most primary literary criticism sources are to be found in the English literary journals. The one good Web site that I can recommend is the Internet Public Library's Literary Criticism.
Otherwise, a good choice is to visit a college or university or large metropolitan public library (central or downtown) and ask the reference librarian on duty to show you these:
One last consideration. You may not find a Web site dealing with the topic you had in mind because it may not be until next week that the site is ready. (The Web changes every day, remember. New sites appear and old ones disappear, without warning -- the latter otherwise known as linkrot!) So, do not give up looking but periodically check back and see if you can find it later!
The World Wide Web is not going to replace a good public library anytime in the near future. It is a good partner for libraries but, as of yet, is no substitute!
See also: Fair Use