Stocks rallied during most of World War II, gaining 157.7% from 1942 low to peak on 29 May 1946. Brief bear market followed till 9 Oct 1946, lasting 133 days down 26.6%. Why? Fear of secular stagnation and a renewed depression. 

Subsequent bull market lasted till 15 June 1948. 615 days up 20.8%. Along the way, 2 significant corrections of declines 14.7% and 14.1%. 

Then a 7 year bull market of 1950s with 4 corrections during Korean War. 

Then 1960s bull market, with a short bear in between for 99 days down 20.7%. 

Then Cuban Missle Crisis which had a bear out for 196 days, creating a 28% dent. In this period, economy grew, despite the Missle Crisis which sparked Cold War jitters. This led to bull being led out for 1324 days, lifting market by 79.8% with just a 10.5% correction in between. 

There were subsequent bulls and bears but two big bears worth noting because when they do appear they are rather significant. The dot.com bubble burst of March 2000 to October 2002. Amazon sat through a very bad 90% drawdown. It was in nascent stages of growth back then. But today it is up 155,000% from its IPO. 

What's the point of history? To teach us that there is always ebb and flow. Two things to pick up from here:

One: There is no continual upward vertical climb. There is a flow. You need know where the flow is heading and be there. But when things get too good to be true, then they are as they are and you need to learn to scale out. 

Two: we need to be a little more contrarian. We tend to do the right things at the wrong time. 

The time to sell is not after a crash. That is the time to buy. And if we have no idea how much lower it can go, then DCA. I had this funny guy posting his portfolio of a tech stock and he bought down on every dollar dip from $45 to about $10, and he called it dollar cost averaging. Most of his capital were expended on the high 30s. He even went to pawn his jewellery to buy a $10 dip and then was completely out of ammo. Was quite candid to share that he could have done better scaling in with a 20% drop each time. Capital conservation works well. 

There are exceptions to this, which are when a trade is completely asymmetrical - risk/reward ratio is completely skewed to an upside. This is when you size in your position BIG to capture the fastest shoot, and then leave. 

It's all fun and games as we continue to navigate this space. Learn well but don't take it too seriously. There is more to life than all the losses and gains in your portfolio!