Although this paper didn't know it at the time, this was one of the first statements of what would eventually be called the Byzantine Generals Problem (there is a paper of that name by the same authors which has similar content, just expanded on a bit).<p>I like Lamport's opinion of his own contribution:<p>"My other contribution to this paper was getting it written. Writing is hard work, and without the threat of perishing, researchers outside academia generally do less publishing than their colleagues at universities. I wrote an initial draft, which displeased Shostak so much that he completely rewrote it to produce the final version."<p>This is one of two great fundamental results in consensus protocols; the other being the later FLP result which shows the impossibility of consensus with failures in an asynchronous network. Byzantine fault tolerance was a hot topic in systems for the last roughly ten years thanks to Turing Award winner Barbara Liskov's work with Miguel Castro on Practical BFT that sparked a bit of a resurgence; the two most notable other papers IMHO in the field since that are 'Separating Agreement From Execution' paper from UT Austin and the SOSP '07 paper on Zyzzyva. Both of these take apart the 3f+1 bound and show exactly how many processors you need for various parts of the protocol.