His ancestors migrated there from Moravia during the reign of Joseph II (1780–1790) his grandfather founding military pharmacies during the Austro-Turkish War of 1787–1791.

[4] As a child, he recalls, I had the greatest pleasure of watching military ceremonies, where I admired the uniforms of the Hungarian generals, as well as spending much time on the ramparts of the fortress of Temesvár.

[7] In 1847 he thought to go to north India, in Lahore[4] and to become an officer in the army of one of the Indian princes, but hearing the news about the revolution from Paris from February 1848 he decided to remain in Hungary.

[5] When in December 1848 the main Austrian imperial troops led by Field Marshal Alfred I, Prince of Windisch-Grätz attacked Hungary, he was appointed as major in the Hungarian army, by 9 January 1849 he was already a colonel.

[5] Klapka defeated him again on 8 February at Hidasnémeti, but the Austrian general was able to retreat towards West, joining the main imperial troops led by Windisch-Grätz.

After Dembiński's order of retreat, at 1 March Klapka fought successful rearguard actions against the Austrian corps led by Ladislaus von Wrbna at Egerfarmos.

[5] At 3 March he was one of the leaders[4] of the revolt at Tiszafüred of the Hungarian officers dissatisfied with Dembiński's leadership, and forced him to resign, supporting Görgei's election to the main command.

Initially, the victory of the Hungarian VII Corps led by András Gáspár against Schlik in the Battle of Hatvan at 2 April, deceived Windisch-Grätz to think that the attack of the Hungarian forces would come from that direction but the failed attack of Klapka's I corps against the Austrian I Corps led by Josip Jelačić in the first phase of the Battle of Tápióbicske (he sent his troops in the city without scouting before that, to see if any enemy troops were in there, thus his troops were ambushed by enemy infantry and a cavalry brigade),[10] forced the III corps led by János Damjanich to intervene, and to turn the tide of the battle – which could have become a serious defeat for the Hungarians – into a victory, made the Austrian Field-Marshal suspicious, that the main Hungarian attack could come from other directions, and not from where he expected that.

[5] Quite in the first day in his office in Debrecen Klapka had a conflict with Sándor Petőfi, the Hungarian national poet, then a major in the Army of Transylvania under the command of Lieutenant General Józef Bem.

[18] Klapka was angered on Petőfi also because of the poet's former conflicts with other Hungarian officers and war ministers like Lieutenant General Antal Vetter and Lieutenant General Lázár Mészáros (against whom he wrote also a satirical poem), so he reprimanded the poet, who came to the war office seeking permission to go to the freshly liberated Pest, to bury his father.

[20] In the middle of May 1849, the news about the upcoming Russian intervention spread throughout Hungary, and the need to take measures against this grave danger became imminent.

[23] Although it was accepted by the Ministry Council on 20 May, this operation plan was met with harsh criticism from Görgei and Bem, who accused it of no concern for the imminent Russian intervention which menaced from North and from East, and that Lieutenant General Bem and General Mór Perczel had been designated to carry out military actions which exceeded their capacities, while the other Hungarian corps were condemned to almost complete inactivity.

[5] In June, when Görgei took over his duties in the War Ministry, Klapka substituted him in the command of the Army of the Upper Danube, being entrusted, together with the chief of the general staff Colonel József Bayer, to attack the imperial forces led by Field-Marshal Julius Jacob von Haynau in the region of the Vág river, and push them towards Pozsony and Vienna,[5] but on 16 June they were defeated by the Austrians in the Battle of Zsigárd.

[4] Their disagreements and contradictory orders affected the Hungarian troops' already weak chances of success during the Battles of Zsigárd, Ihász and Győr.

Klapka and the officers refused to fulfill both these orders, forcing the government to accept their decision to remain for several days in Komárom, and to keep Görgei as their commander.

[30] On 7 July, on the order from Kossuth, Klapka sent the I. corps led by General Nagysándor towards Szeged, but when Görgei took notice of this, he resigned from the leadership of the Army of the Upper Danube, to protest this decision taken without his knowledge.

Hearing about this Klapka ordered the I. corps to return to Komárom, as a result of which Görgei retracted his decision, remaining the commander of the army.

[35] As the captain of the encircled fortress, cut off from the other Hungarian armies, Klapka decided to make a heroic stand against the superior enemy, to resist until nothing more could be done, and if he would be forced to leave Komárom, he would do it only with honour.

[37] In the night of 3 August 1849, Klapka personally led the Hungarian troops to the right bank of the Danube, attacking the Austrian blockade around the fortress, crushing the imperial forces led by Lieutenant Field Marshal Anton Csorich in the Fourth Battle of Komárom, causing them 1,500 casualties, capturing 30 cannons, many thousands of rifles, ammunition and an entire herd of oxen.

[36] During the Austro-Russian siege the Hungarian composer Béni Egressy who was in the besieged Komárom, wrote the Klapka March, in honor of the general.

[36] This was rejected, Lieutenant Field Marshal Anton Csorich demanding unconditional surrender, so the Hungarians decided to continue the resistance.

[36] Haynau understood that taking Komárom would be a very hard and long task that would cause thousands of deaths among his troops, so he decided to seek a compromise with Klapka and the defenders.

These conditions were as follows: - The soldiers could leave without their arms, while the officers could leave retaining theirs; - Those officers who prior to the Hungarian War of Independence were in the Austrian army, received passport to leave the country; - Those who did not wanted to leave could return home, without being prosecuted; - Those Hungarian officers who prior to the war were not in the Austrian army could return home, they were free to work in any profession, start businesses, but they were prohibited to be conscripted in the army again; - The former soldiers of the Habsburg armies received total amnesty; - Those who wanted to leave the country, had to ask for passports in 30 days; - The officers received payment for 30 days, while the simple soldiers for 10 days in Austrian banknotes[36] (equivalent to 500 000 Forint's);[4] - The vouchers used as money by the soldiers and the people of Komárom during the siege, would be redeemed in Austrian banknotes; - The crippled, the sick and the wounded people and soldiers who were in the hospitals of Komárom would receive medical attendance; - Everybody would retain their personalities and realties.

[46] Before the fortress was handed over on 2–4 October, Klapka bid farewell to his soldiers which ended with these lines: You have bowed before the iron stick of the events - this circumstance and the honor [of our nation] you have saved should be a comfort to you all!

[3] He continued by every means in his power to work for the independence of Hungary, especially at moments of European wars, such as 1854, 1859 and 1866, at which an appeal to arms seemed to him to promise success.

[2] He tried to create an alliance with the states and nations which were neighbours with Hungary, like the Principality of Serbia or Moldavia and Wallachia, and supported the Polish Uprising of 1863–1864 against Russia.

[2] The only problem was that the Prussians gave him the acceptance to organize the Hungarian legion too late, after their decisive victory over the Austrians in the Battle of Königgrätz.

[2] After the Austro-Hungarian Compromise of 1867 Klapka was permitted to return to his native country, but as well as in the case of Artúr Görgei, the emperor Franz Joseph I of Austria did not allow him to join the army, because he did not forgive his campaign attempt in Hungary from 1866.

[2] As a result of this Klapka turned to politics, between 1868 and 1872 becoming member of the right wing Deák Party, being elected in the Hungarian Parliament as a deputy of Illava, then his hometown Temesvár.

[7] He was slender, of medium stature, with an elegant, delicate appearance: his dark glossy, moony eyes showed a spirited, poetic personality, fiery bravery and seas of beautiful conceptions.