C-B-A-R is the acronym for the correct way to swim a 200 event. The first 75 of your swim should be “easy speed”, in that you are going fast, but also swimming relaxed. we call this the Cruise portion of your race. If you can be at the 75 mark, with a relatively low heart rate (but a solid split), you have effectively won the race. Why? If your opponent exerts too much effort on the first 75, they will not be able to sustain that effort over the next 125. Since your heart rate is lower, you have the advantage. The next 50 of your race is a Build, where you gradually build your speed into the next 50. This is the Attack portion of your race. The last 25 (more if you can handle it) is the Race portion of the 200. This is where you have the most advantage over your opponent.
Of course, the C-B-A-R strategy can, and should be, individualized. Experiment in practice so that you can maximize your velocity over the last 75 of your 200. Once accomplished, you have the upper hand!