So Gilbert went to Flanders in 1572 with 1400 Englishmen to fight against Philip's stern deputy, the Duke of Alva. He took part in the siege of Sluys, and wrote to ask the Queen for more men to be sent. He then helped in the assault on Tergoes. But his rash, hot-headed style of fighting, acquired perhaps in Ireland, offended the slow and cautious Dutchmen whom he was assisting, and Gilbert returned to England, convinced that the Dutch lacked animal courage. Then for two years Sir Humphrey lived quietly at Limehouse, busy with chemical researches; but as his partners wished to try the so-called science of alchemy and to transmute iron into copper, he begged leave to withdraw, mistrusting their modicum of science. Gilbert had time to meditate now on his relentless treatment of Irish rebels. A brave and chivalrous gentleman, for those times, a scientific explorer and a man of deep piety, he could now compare his conduct in Ireland with Alva's in the Netherlands, and wonder if Sidney's high praise had been deserved. "For the Colonel," Sidney wrote to Cecil in 1570, "I cannot say enough. The highways are now made free where no man might travel unspoiled. The gates of cities and towns are now left open, where before they were continually shut or guarded with armed men.... And yet this is not the most, nor the best that he hath done; for the estimation that he hath won to the name of Englishman there, before almost not known, exceedeth all the rest; for he hath in battle broken so many of them, wherein he showed how far our soldiers in valour surpassed those rebels, and he in his own person any man he had. The name of an Englishman is more terrible now to them than the sight of a hundred was before. For all this, I had nothing to present him with but the honour of knighthood, which I gave him; for the rest, I recommend him to your friendly report." That was the better side of the question--order kept and duty done. But Sir Humphrey in his two years of quiet thinking and writing must have often recalled with compunction scenes in Ireland which he could not approve of, and perhaps was dimly conscious of at the time. For the English troops, spread abroad over a lonesome countryside and held in check only by some ruthless sergeant-major, would often, when opposed to desperate men, meet outrage with outrage, and cruelty with cruelty. Sidney himself loathed his vile task, and often implored to be called away from "such an accursed country." We may be sure, then, that a man so gentle and humane as Sir Humphrey Gilbert must have felt that the government of Ireland was no pleasant task. It was also very expensive, for the cost of it to England above the revenue levied in Ireland itself from the date of Elizabeth's accession was now £90,000.