Was field Marshall Haig popular

Yes... Haig was hugely respected/ admired in the immediate aftermath of World War One. He campaigned vigorously for veterans (see the Haig Poppy appeal etc), and most veterans of "The Great War" regarded him as a "Great Man". General "Black Jack" Pershing of the US Army called him "The man who won the war".

After his death, however, and towards the end of the 1920s (especially following the publication of certain memoirs, plays - notably RC Sheriff's "Journey's End" - and poetry - eg Wilfred Owen) a growing pacifist mood pervaded Britain. There was widespread disillusion following the General Strike, 1926, and the Wall Street Crash of Oct 1929 and subsequent Great Depression (and consequent rise of European Dictators etc) intensified this. Surviving Great War politicians (notably Lloyd-George) also published memoirs in which Haig (recently deceased) was scapegoated for all the shortcomings of the Great War's conduct - conveniently, he could not respond, and nor could he sue!

So, over time, Haig became a convenient repository/ scapegoat for all bitterness relating to the First World War, and in the minds of many (especially on the Left) he came to symbolise all that was wrong with the ruling elite. This perception was reinforced again in the 1960s by plays like "Oh! What a Lovely War!" (produced by a Marxist Theatre "collective") and the commercially very successful film based on it. "Haig bashing" was the default setting of the prevalent Left/ Liberal "intelligensia" and "counter culture" of the period.

Since then, however, most serious military historians (eg John Terraine, Gary Sheffield et al) have done much to cut through all the myths and sentimental balony that had grown up around Haig, and there is a better founded appreciation of what a capable commander he really was. The majority of soldiers who served under his command always acknowledged this - it's just that a changing world could not (especially from mid C20th/ post the even greater horrors of WW2) quite come to terms with the horrendous reality of what was necessary to beat the might of the Kaiser's Armies in the Main Theatre of Operations of World War One!

Simple facts: from mid 1916 it was the British Army commanded by Douglas Haig that took on the main burden of fighting the main army of the primary enemy in the most important theatre of operations of the Great War (WW1). That army became, under Haig, the most formidable instrument of war in the World at the time (even the French acknowledged this!), and ultimately led the Allies in the crushing of the Imperial German Army.

Yes, American help was invaluable (probably shortening the war by 6 months to a year); the French contributed massively (as they had done from the outset, having done most of the really heavy fighting from 1914-16), but it was the Battle of Amiens/ the Hundred Days, and especially the magnificent breaching of the "impregnable" (in French and American estimation) Hindenburg Line, which finally broke German resistance.

As Gen Pershing, US Army, not known for his pro-British sentiments, noted afterwards, it was Haig's army that led the Allied Offensive, demonstrating a quite remarkable capability in fighting a dynamic, "all arms", battle of great tactical flexibility and innovativeness. Haig was quite simply THE man of the moment. No other British general (with the possible exception of Marlborough in the C18th) has ever, before or since, matched his achievements. Everyone knew this at the time - which is why Haig was so highly honoured after the war, but the British have since (with, some might say, characteristic perversity!) somehow forgotten this, and come to believe Haig was, at best, incompetent, and more likely a murderous idiot. He was not, and deserves, in truth, to be remembered as one of history's "Great Commanders".