Imperial army under Montecuccoli entered Transilvania, August 1661

In August of 1661 Emperor Leopold I sent an army under FM Raimundo Montecuccoli in Transilvania to support Janos Kemeny (see Wiki for more details). It consisted of 16 regiments zu Pferd, one of Croats, 6 Frei-companies & 15 regiments zu Fuss in 3 Corps:

• Feldmarschall-Leutenant Johann Reichard graf Starhemberg: 2 regiments zu Pferd (Heister, Knigge) & 4 regiments zu Fuss (Johann Reichard Starhemberg, Ludwig Raduit Souches, Otto Wallis, Cobb) 
• Feldmarschall Raimundo Montecuccoli: 9 regiments zu Pferd (Raimund Montecuccoli, prince Ruppert, Pfalzgraf von Simmern-Zweibruckn, Iohann Sporck, Franz Scheidau, Clemens Caprara, Fabri, Peter Buschieri, Mainz regiment under Bosfeld), one of Croaten (Souschentz), 3 Bavarian Frei-companies under Obrist-Leutenant Nikolaus Honning, 5 regiments zu Fuss (Markgraf Leopold Wilhelm von Baden, Peter Strozzi, Cobb, Bavarian regiment Puech of 8 coys, Coln regiment Roist of 11 coys) 
• Feldzeugmeister Ludwig Raduit Souches (Komorn): 5 regiments zu Pferd (GFWM Sigmund Friedrich graf von Gotz, Schaaf, Enea Silvio graf Piccolomini, Bernhard Walther, Beichere), 3 Kurmainz Frei-company, 6 regiments zu Fuss (La Cron, Adolf Buchheim, Franz de Mercy, regiments from Munster, Mainz & Wurzburg) 

Their campaigns of 1661-62 were a prelude to the Austrian-Turkish war of 1663-64.

Source: Staudinger's Geschichte des bayerischen Heeres: Geschichte des kurbayerischen Heers insbesondere unter Kurfurst Ferdinand Maria 1651-1679. SS. 494-495.