Reddit mentions of The Monetary Policy of the Federal Reserve: A History (Studies in Macroeconomic History)

To further confuse the issue, Roosevelt's New Deal (which Keynesians will attribute to ending the Great Depression) was implemented concurrently with relatively aggressive monetary policy as well. Both actions were designed to help end the Great Depression.

Between May 1928 and August 1929, the Fed raised its discount rate from 3.5% to 6% (the "discount window" is a mechanism by which banks can borrow directly from the Fed on a very short term basis to meet temporary liquidity shortages. Historically, this rate has been lower than the rate banks can get on the open market. Thus, it provides sort of a floor for market interest rates. An increase in the discount rate, then, will result in an increase in the market interest rate [to be even more exact, the "interest rate" is the rate on a short term Repo]. This increase makes it more expensive for banks to borrow, which in turn makes it more expensive for everybody to borrow).

This caused the money stock to fall by a third from 1929 to 1933. This contraction in money stock caused deflation. The resulting deflation meant that by in 1929, 1930, and 1931 real interest rates on commercial paper were 6.7%, 5,7% and 9.7%, respectively. The Fed had the ability (though not necessarily the political will, or even the desire) to stem this contraction, but decided not to act This is the monetary tightening that Monetarists will claim unnecessarily contributed to the continuance of the Depression.

These actions, in turn, were caused by a plethora of factors, including a lack of consensus within the economic profession on how monetary policy affected the economy. Also, part of the reason why the Fed raised interest rates was because they (not just people within the Fed, but many other critics) feared they were fueling a speculative bubble in the stock market in the latter part of the 1920's. They feared that injecting liquidity into the banking system in the early 1930's would revive securities speculation.

In any event, in April 1933, the new Roosevelt administration made it clear that they were going to actively work to depreciate the dollar to raise domestic prices (this might be confusing, but basically, you should look at inflation and exchange rates as different sides of the same coin. Depreciating the dollar = making the dollar weaker = one dollar buys you less stuff = prices go up = inflation). They did this by buying tons of gold on the open market (buying more gold = selling more dollars = increasing the supply of dollars = lowering the price of dollars = depreciating the value of the dollar = ... = inflation). By this point, banks had stopped borrowing from the Fed's discount window, which means the Fed had basically lost control of monetary policy. In other words, Roosevelt's Treasury Department took over control of implementing monetary policy.

In January 1934, the US fixed its purchase price of gold at $35/oz. Because the US was on the gold standard, this meant a 59% devaluation of the dollar basically overnight. The money supply drastically increased after this action. Real GNP also proceeded to rise drastically from 1934 to 1937.

Real GNP took a dive again in 1937 on the heels of the Fed's decision to massively raise the reserve requirement for banks. This was done to attempt to reassert control over monetary policy (Fed monetary policy is basically implemented by manipulating either interest rates or reserve requirements. By 1933, banks had accumulated so much extra reserves that they no longer needed to borrow from the Fed, thus depriving the Fed of that tool. By jacking up reserve requirements, the Fed attempted to wipe out the banks' caches of excess reserves, which would then force banks to go back to borrowing from the Fed). This move was eventually neutralized by the banks (who accumulated more excess reserves), and real GNP started to grow again in June 1938.

The difficulty is assessing the relatively impacts of both programs. I'm no expert on the New Deal, so I'll leave that discussion for someone who knows better.

TL;DR - the Roosevelt administration simultaneously implemented aggressive Keynesian and Monetarist policy. Both arguably achieved their goals, and the real problem lies with assessing the relative impacts of both programs.

Source for the monetary history and numbers:
The Monetary Policy of the Federal Reserve: A History by Robert L. Hetzel, Cambridge University Press 2008