1.  Marriage Record:

2.  1860 Census Every-Name-Index/Images (online at Ancestry.com, Image #7 of 13):  Jonesville P.O., Fayette Twp., Hillsdale Co., MI, Roll 653_543, p. 698, PN 78, 572/572, enumerated 9 Jul 1860, official enumeration date 1 Jun 1860 (extracted by Diana Gale Matthiesen):¤•

Conrad Stroup

30

M

Bachelor Farmer

400

Baden

3.  1880 Census Every-Name-Index/Images (online at Ancestry.com):  can't find Sophia, at all.  Can't find Catharine KLOTZ with any certaintly.

4.  Anon.  1997-2000.  Military Records of Individual Civil War Soldiers.  Historical Data Systems, Provo, UT (online at Ancestry.com):

Name:	Conrad Straub
Residence:	Hillsdale County, Michigan
Enlistment Date:	29 December 1863
Distinguished Service:	DISTINGUISHED SERVICE
Side Served:	Union
State Served:	Michigan
Unit Numbers:	1104 1104
Service Record:	Enlisted as a Private on 29 December 1863 at the age of 35. Enlisted in Company K, 27th Infantry regiment Michigan on 05 January 1864. Wounded on 06 May 1864 at Wilderness, VA. Died of wounds Company K, 27th Infantry Regiment Michigan on 21 June 1864.

5.  Civil War Pension Index (index and images online at Ancestry.com):

Name of Soldier	Straub, Conrad
Name of Dependent	Widow	Straub, Sophia
	Minor	Klotz, Catharine (Gdn)
Service	K 27 Mich. Inf.
Date of Filing	Claim	Application No.	Certificate No.	State from which Filed
	Invalid
1864 Dec ??	Widow	75281	50753
1866 Mch 19	Minor	123607	76089

The numbers were blurred and hard to read, so my extraction may not be entirely accurate.  It seems unlikely that Catharine would have applied for a minor's pension if Sophia hadn't died.  The pension applications would likely reveal a great deal about Conrad's family, Sophia's family, and Catharine's family.