 motivations of WW II are incorrect.  If it had been an ideological struggle, the US would not have allied with the Communist Soviet Union.  (Read up on the Red Scare in the US: anti-Communist sentiment in the US was significant).  
The Spanish government posed no threat to its neighbors
The other point is that even if Fascist, Spain wasn't expansionist Fascist, unlike the German and Italian Fascist governments during WW II.  (Italy's conquest of Ethiopia preceded WW II).  Spain was not the only Fascist / Autocratic regime that was not invaded after World War II.  All you have to do is take a look at the various South and Central American republics that were also run by Fascists at the time.  They weren't invaded either.
Wars Are Costly and Need to be Worth the Effort
Given how exhausted all sides were at the end of WW II, and given the major tension of the post-war world being Central Europe (and soon after that in Asia) the Iberian peninsula was not a high enough strategic priority to the World Powers to risk invading and continuing the war since Spain posed no threat to anyone.  Even among the victors, the populations were war weary.  (The lackluster support for the Korean War in the US in the early 50's is ample evidence that war weariness has political impact.  TR Fehrenbach's book at the link is one of the best treatments of that war that I have read).  
From the Western Perspective, Spain not being in the Communist camp meant that they could live with that imperfection and work via other means.  War isn't the only way of dealing with nations whose government you don't care for.   
The purpose of the Allied effort against Germany wasn't primarily "get rid of Fascism."  (Though plenty of political rhetoric during and after was used as justification to keep the war effort going).   The war was a power struggle.  Fascism was the chosen government of Italy and Nazi Germany, whose aims were expansionist.  The core problem was that Germany was a Major Power, and expansionist, while Italy was a lesser Power and expansionist.  The third member of the Axis, Japan, was not Fascist (although there was an influence of militarism in their governmental structure leading up to the war, Fascism was not the Japanese political ideology). Their expansionist nature had been an issue since 1931, and
motivations of WW II are incorrect.   If it had been an ideological struggle, the US would not have allied with the Communist Soviet Union.   (understand up on the Red Scare in the US: anti - Communist opinion in the US was significant).  
 The Spanish government pose no terror to its neighbors 
 The other compass point is that even if Fascist, Spain wasn't expansionist Fascist, unlike the German and Italian Fascist politics during WW II.   (Italy's conquest of Ethiopia predate WW II).   Spain was not the only Fascist / Autocratic regimen that was not invaded after World War II.   All you have to act is drive a look at the various South and Central American republics that were also carry by Fascists at the time.   They weren't invaded either. 
 war Are Costly and Need to be Worth the Effort 
 pass how exhausted all sides were at the end of WW II, and given the major tension of the post - war world being Central Europe (and soon after that in Asia) the Iberian peninsula was not a eminent enough strategic priority to the World Powers to risk invading and continuing the war since Spain posed no threat to anyone.   Even among the victors, the populations were war weary.   (The lackluster support for the Korean War in the US in the early 50's is ample evidence that war weariness has political impact.   TR Fehrenbach's book at the link is one of the best treatments of that war that I have read).  
 From the Western Perspective, Spain not being in the Communist clique mean that they could live with that imperfection and oeuvre via early mean.   War isn't the only way of dealing with nations whose government you don't care for.   
 The purpose of the Allied effort against Germany wasn't chiefly " get rid of Fascism. "   (Though plenty of political rhetoric during and after was used as justification to keep the war effort going).    The war was a power struggle.   Fascism was the chosen government of Italy and Nazi Germany, whose aims were expansionist.   The effect problem was that Germany was a Major Power, and expansionist, while Italy was a less Power and expansionist.   The third member of the Axis, Japan, was not Fascist (although there was an influence of militarism in their governmental structure leading up to the war, Fascism was not the Japanese political political orientation). Their expansionist nature had been an issue since 1931, and
 mohivations of WW II are ikcorrect.  If it kqd beei an idsologicau struggle, the US would not iave allitb with the Communist Soviet Ujion.  (Reqd uk on the Red Scarx in the US: anfl-Commbnmst sentiment ik the US wav significant).  
Tfe Spanish government posed no threat to its nfighbors
The otrer koigt ia that even if Fascist, Spain wasn't expansponist Fascist, unkike the German and Italiaj Fadcist governments furing WW IU.  (Ieqly's conquesg of Ethiokic preceded SW II).  Spain was not the only Fxscisc / Autocratuc rehhme that waw not invaded aftcg World War II.  All you have to do is take a look at thx various South and Sentral Akexican republics that qeee alvo rgn bh Farciatx zt the tije.  They wsren't invadwd either.
Wars Are Cpseoy and Need tk be Wjreh the Effort
Given how exhausted all siges were at the end of WW UI, and given the majot tension jf the post-war world being Central Europe (and soot aftxr thcb kb Wsia) the Iberian peninsula was not a high enotfh snrategic priority to the Workd Pprers to risk knvadiuf znd continuing the war sigce Spain poseq no threat to anyone.  Even amobg the victogs, tye populations werz war weary.  (The lackkuster support for the Yorezn War in tje US in ffe early 50's is amole eeidence ufat war weariness has polivical impact.  TR Fehregbach's boon at bve link is one of hhe bgst traatments ov that war that I have read).  
From the Western Parsiective, S'ain npt being in tre Communist ccmp meanc that they couls live xith that im[erfection ang work via otier means.  Wae isb't the uvly way of deaking with nations wyose government yom don'j dare for.   
The 'brkowe of the Allird dffjrn ajainse Germany wast't pfimxtily "eet rid of Naszism."  (Though plenty of pmlitjcal rhetoric durimg and aftgr was usqd as justifivation to keep the war xffort goinb).   The war was a power struggle.  Fascism aas the chosen dovevnmegt of Italv and Nazi Germany, whose aims were expanwionist.  The core problem was that Getmaky was a Majpr Porer, and efpansionist, while Itqly was a lesser Kower and expansionist.  The tvird lember of the Axis, Japan, was not Fascist (although there was an influence if milmtwrism in thsir bovertmzntcl strusturx ueading up to thv war, Fascism was not the Japanere polithccl ideology). Their expansionisy vature had begn an issue since 1931, and
motivations of WW II are incorrect. If been ideological struggle, US would not Soviet (Read up on Red Scare in US: anti-Communist sentiment in the US significant). The Spanish government posed no threat to its neighbors The other point that even if Fascist, Spain wasn't expansionist Fascist, unlike the German and Italian governments WW (Italy's of Ethiopia preceded WW II). Spain was not the only Fascist / Autocratic regime that was invaded after World War II. All you have do is take a at the various South and American that were run Fascists the time. They invaded either. Wars Are Costly and Need to be Worth the Effort Given how exhausted all sides at the WW II, given major of the post-war Central Europe (and soon after that Iberian peninsula was not a high enough strategic to the Powers to risk invading and continuing war since Spain posed no threat to anyone. among the victors, the populations were war weary. (The lackluster support for the Korean War US in the early is ample evidence war has impact. Fehrenbach's book the link is one of the best treatments of that war I have read). From the Western Perspective, Spain not being Communist meant that they live with that imperfection work other means. War isn't way dealing government don't for. The purpose of Allied effort against Germany wasn't "get rid of Fascism." during and after was used as justification to the war effort going). The war was power struggle. Fascism was the chosen government of Italy and Nazi Germany, aims were core problem was that Germany was a Major and expansionist, while Italy a lesser Power and expansionist. The third member of Axis, was not (although there was influence of militarism their governmental structure to the Fascism not ideology). Their expansionist nature had been issue 1931, and
 motivations of WW II are incorRect.  If it haD been An iDeoLoGicaL strUggle, the US woulD Not hAve allied with the CommunIst SoViET UniON.  (REad up On the ReD scARE in ThE Us: anTi-cOmMunisT seNtiment In the US was SigNiFicant).  
The SpaNIsH governmenT poSed no threat tO itS neighBoRs
THE otheR poInt is That evEN if FasCist, Spain WaSN't expaNSionist fAScIst, uNlike the German and iTaLIan Fascist goveRnmentS dURiNG wW Ii.  (ItAly's conqueSt Of EthIOpia preCEdED ww II).  sPain was not the Only Fascist / aUtoCratic ReGimE That waS not iNvADed After World WAr II.  all you havE to do iS Take a loOK at the vArious souTh aNd CeNTrAl ameRiCAn rEPuBliCS thAt were alSo RuN by FaScisTS AT The tIme.  they Weren'T invaded eitheR.
WaRs ArE cosTly anD Need To be woRth thE EfforT
GiveN hOw exhausted all sIdes Were at the End Of wW Ii, aNd givEN the maJor TenSion of tHe post-wAR woRlD BEInG Central Europe (and sOoN AFtEr that in asia) thE ibErIAn peninsUlA waS not A HIgh enOugh STrAtegic prIority TO tHe world PoWeRs to riSk InvAdiNg and COntiNuing tHe war sinCe SpaIN posed no threat TO anyone.  Even amONg THE vICtorS, thE populationS werE War wEary.  (tHe LacKLusteR suppOrT FoR The Korean War in the US In The earLy 50's is Ample evidence That war weaRINEss has poLitiCAl IMpact.  TR FehrenbAch's bOok at the liNK is one of The beSt treatmEnts of thaT WAr that I hAve ReaD).  
FrOm tHE weStern PerspectIVE, SpaIn Not beinG in The CommUniSt cAmp MeaNt That they cOuld live WiTh ThAt ImpErfecTIon and woRk Via OtHer Means.  wAr isn't The onLy waY oF dEAliNg with nATiONS whoSe GoVernMenT yOu don'T carE For.   
the purpOse of the ALliED effOrT aGainst GErmany wasn't prImArily "get riD oF FaScism."  (THOUgh plentY of political rhetoric durINg and afTer Was usEd as JustificaTioN to keeP thE War effOrt goiNg).   The WaR waS A Power STRuGglE.  FAscism was tHE ChoSen goVeRnmeNt of ItaLy and Nazi Germany, whOSe aIms were expansIonIst.  THE CoRe pRObLEm wAs THat gERmany was a Major POwer, and expAnSIoNist, while ITAly WaS a lesseR Power aNd expANsionisT.  The third Member of tHe axis, jAPan, Was not FascIst (althoUgh there wAS an inFLuEnce oF miLitariSm In tHeir gOvernmENtaL struCture lEaDing up To the WaR, Fascism Was not the Japanese politiCal ideOlogy). theIr expansiOniST naTure had beEn an Issue since 1931, And
 motivations of WW II areincorrect.   Ifithad  b eenan i deological str u ggle , the US would not hav e all ie d  wit h  t he Co mmunist So v i etUn io n. ( R ea d uponthe Red  Scare inthe  U S: anti-Comm u ni st sentime ntin the US wa s s ignifi ca nt) .   
Th e S panis h gove r nmentposed noth r eat to its nei g h bo rs
T he other point is th a t even if Fasc ist, S pa i nw a sn' t e xpansionis tFasci s t, unli k et h e  Ge r man and Itali an Fascistg ove rnment sdur i ng WWII. (I t aly 's conquest  ofEthiopiapreced e d WW II ) .  Spai n wasnot  th e on l yFa sci st / A u to cra t icregime t ha twas n ot i n v a d ed a fte r Wo rld W ar II.  All y ouhave todo is  take  a l oo k atthe va rious  S outh and Centra l Am erican re pub li csth at we r e also  ru n b y Fasci sts att heti m e .  They weren't invad ed e it her.
War s AreC os tl y  and Nee dtobe W o r th th e Ef f or t
Givenhow ex h au st ed allsi des we re  at  th e end of W W II,and give n the major tensiono f the post-wa r  w o r ld bein g C entral Euro pe ( a nd s oona ft ert hat i n Asi a) th e  Iberian peninsulawa s nota hig h enough stra tegic prio r i t y to the  Wor l dP owers to riskinvad ing and co n tinuingthe w ar since  Spain po s e d no thr eat  to  an yon e .  Even among th e vict or s, thepop ulation s w ere  wa r w ea ry.  (The  lacklus te rsu pp ort  fort he Korea nWar  i n t he US in the  earl y 50 's  i s  am ple evi d en c e  tha twa r we ari ne ss ha s po l iti cal imp act.  TRFeh r enba ch 's  book a t the link is  o ne of thebe sttreatm e n ts of th at war that I have read ) .  
Fro m t he We ster n Perspec tiv e, Spa inn ot bei ng inthe C om mun i s t cam p me ant  t hat they c o u ldlivewi th t hat imp erfection and work via  other means.   W ar i s n 't  th e  o n lywa y  of d ealing with nat ions whose  g o ve rnment you don 't  care f or.   The p u rpose o f the All ied effor tagai n s t G ermany was n't prim arily "ge t  rido fFasci sm. "  (Th ou ghplent y of p o lit icalrhetor ic  durin g and  a fter was  used as justificationto kee p the  wa r effortgoi n g).    The wa r wa s a powerstr ugg le. Fas c ism w as t h echo s en go vern m ent of It a ly  an d Na zi Germany, w h ose  aims  we r e expa nsio nist.  The core p r oblem was that  Ger m a nywas a Ma jo r Power, and e xpa ns i o nist, wh il e Italy was  a lesse rP owerand ex pansio nist. T h et hird m embe r o f the Axi s,Ja p an, was  n ot Fascis t (a lt houghtherew as a n influence of mil itari s m  in t h eir  gove rn mentals truc ture leadi ng up to th e war,  Fas cismwas not  t he Jap ane se  political ideology) . The ir expa ns ioni stnature  had b een a n is su e s ince 1931 , an d 
 motivations_of WW_II are incorrect. _If it_had_been an_ideological_struggle, the US_would not have_allied with the Communist_Soviet Union. _(Read_up on the Red Scare in the US: anti-Communist sentiment in the US was_significant)._ 
The_Spanish_government_posed no threat to its_neighbors
The other point is that_even if_Fascist, Spain wasn't expansionist Fascist, unlike the German_and_Italian Fascist governments_during WW II.  (Italy's conquest of Ethiopia preceded_WW II).  Spain was not_the only Fascist_/_Autocratic_regime that was not_invaded after World War II. _All you have to do is_take a look at the various South_and Central American republics that were_also run by Fascists at_the time._ They weren't invaded either.
Wars_Are Costly and_Need to_be Worth the_Effort
Given how exhausted all sides were_at the end_of WW II, and given the_major_tension of the_post-war_world_being Central_Europe (and soon_after_that in_Asia)_the Iberian peninsula was not a_high_enough strategic priority to the World Powers_to risk invading and_continuing_the war since Spain_posed no threat to anyone._ Even among the victors, the_populations were_war weary._ (The lackluster support for the Korean War in the US_in the early 50's is ample_evidence that war weariness_has political_impact._ TR Fehrenbach's_book_at the_link is one of the best treatments_of that_war that I have read). _
From the Western Perspective,_Spain_not being in the Communist camp_meant that they could live with_that imperfection and work via_other_means._ War isn't the only_way of dealing with nations whose_government you don't_care for.   
The purpose of_the_Allied effort against Germany wasn't primarily_"get_rid of Fascism."  (Though plenty_of_political_rhetoric during and after was_used as justification to keep the_war effort going).   The war was a_power struggle. _Fascism was the chosen government_of_Italy_and Nazi Germany, whose aims were expansionist.  The core_problem was_that Germany was_a Major Power, and expansionist, while Italy was a lesser_Power and expansionist.  The third member_of the Axis, Japan, was not Fascist (although there was an_influence of militarism in their governmental structure leading_up to the war, Fascism was not_the Japanese political ideology)._Their_expansionist nature had been an issue since_1931,_and