If one turns aside from the devastating human tragedy and wasted potential consequent upon the Republic's military defeat in 1939, to examine the political cost of that defeat to the component organisations of the Republican side, then none was worse affected than the Spanish socialist movement, comprising the party (PSOE) and union (UGT). After half a century's existence, the party which had sustained the Republic from its birth in 1931, was all but annihilated by the experience of the civil war. The PSOE would only be restored to its leadership position in Spain's political life in the 1970s. But the Socialist Party which emerged then, although claiming historical continuity, bore little resemblance to its predecessor. It was a new party for a new Spain. The defeat of the Republic in April 1939 had precipitated the final crisis of the ‘historic’ PSOE. But while the PSOE's disintegration was a function of the Republic's own, the reverse was no less true, as this study seeks to